diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c1b6569..55986de6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 master
 ===
 
+* Switch from Ruby Sass to SassC.
 * `relative_assets` extension overrides local `relative: false` option to stylesheet/javascript tag helpers.
 
 # 4.0.0.rc.1
diff --git a/middleman-core/features/slim.feature b/middleman-core/features/slim.feature
index 2cdabecd..031120f3 100644
--- a/middleman-core/features/slim.feature
+++ b/middleman-core/features/slim.feature
@@ -78,4 +78,4 @@ Feature: Support slim templating language
     When I go to "/sass.html"
     Then I should see "html,body,div"
     When I go to "/error.html"
-    Then I should see "Error: Invalid"
+    Then I should see "Error:"
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_base.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_base.scss
new file mode 100644
index 00000000..b7659885
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_base.scss
@@ -0,0 +1,15 @@
+// Bitters 1.1.0
+// http://bitters.bourbon.io
+// Copyright 2013-2015 thoughtbot, inc.
+// MIT License
+
+@import "variables";
+
+// Neat Settings -- uncomment if using Neat -- must be imported before Neat
+// @import "grid-settings";
+
+@import "buttons";
+@import "forms";
+@import "lists";
+@import "tables";
+@import "typography";
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_buttons.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_buttons.scss
new file mode 100644
index 00000000..6ac7894f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_buttons.scss
@@ -0,0 +1,35 @@
+#{$all-buttons} {
+  appearance: none;
+  background-color: $action-color;
+  border: 0;
+  border-radius: $base-border-radius;
+  color: #fff;
+  cursor: pointer;
+  display: inline-block;
+  font-family: $base-font-family;
+  font-size: $base-font-size;
+  -webkit-font-smoothing: antialiased;
+  font-weight: 600;
+  line-height: 1;
+  padding: $small-spacing $base-spacing;
+  text-decoration: none;
+  transition: background-color $base-duration $base-timing;
+  user-select: none;
+  vertical-align: middle;
+  white-space: nowrap;
+
+  &:hover,
+  &:focus {
+    background-color: shade($action-color, 20%);
+    color: #fff;
+  }
+
+  &:disabled {
+    cursor: not-allowed;
+    opacity: 0.5;
+
+    &:hover {
+      background-color: $action-color;
+    }
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_forms.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_forms.scss
new file mode 100644
index 00000000..e8ae80a2
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_forms.scss
@@ -0,0 +1,90 @@
+fieldset {
+  background-color: $secondary-background-color;
+  border: $base-border;
+  margin: 0 0 $small-spacing;
+  padding: $base-spacing;
+}
+
+input,
+label,
+select {
+  display: block;
+  font-family: $base-font-family;
+  font-size: $base-font-size;
+}
+
+label {
+  font-weight: 600;
+  margin-bottom: $small-spacing / 2;
+
+  &.required::after {
+    content: "*";
+  }
+
+  abbr {
+    display: none;
+  }
+}
+
+#{$all-text-inputs},
+select[multiple=multiple] {
+  background-color: $base-background-color;
+  border: $base-border;
+  border-radius: $base-border-radius;
+  box-shadow: $form-box-shadow;
+  box-sizing: border-box;
+  font-family: $base-font-family;
+  font-size: $base-font-size;
+  margin-bottom: $small-spacing;
+  padding: $base-spacing / 3;
+  transition: border-color $base-duration $base-timing;
+  width: 100%;
+
+  &:hover {
+    border-color: shade($base-border-color, 20%);
+  }
+
+  &:focus {
+    border-color: $action-color;
+    box-shadow: $form-box-shadow-focus;
+    outline: none;
+  }
+
+  &:disabled {
+    background-color: shade($base-background-color, 5%);
+    cursor: not-allowed;
+
+    &:hover {
+      border: $base-border;
+    }
+  }
+}
+
+textarea {
+  resize: vertical;
+}
+
+input[type="search"] {
+  appearance: none;
+}
+
+input[type="checkbox"],
+input[type="radio"] {
+  display: inline;
+  margin-right: $small-spacing / 2;
+
+  + label {
+    display: inline-block;
+  }
+}
+
+input[type="file"] {
+  margin-bottom: $small-spacing;
+  width: 100%;
+}
+
+select {
+  margin-bottom: $base-spacing;
+  max-width: 100%;
+  width: auto;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_grid-settings.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_grid-settings.scss
new file mode 100644
index 00000000..8a98a743
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_grid-settings.scss
@@ -0,0 +1,14 @@
+@import "neat-helpers"; // or "../neat/neat-helpers" when not in Rails
+
+// Neat Overrides
+// $column: 90px;
+// $gutter: 30px;
+// $grid-columns: 12;
+// $max-width: 1200px;
+
+// Neat Breakpoints
+$medium-screen: 600px;
+$large-screen: 900px;
+
+$medium-screen-up: new-breakpoint(min-width $medium-screen 4);
+$large-screen-up: new-breakpoint(min-width $large-screen 8);
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_lists.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_lists.scss
new file mode 100644
index 00000000..c989d90f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_lists.scss
@@ -0,0 +1,31 @@
+ul,
+ol {
+  list-style-type: none;
+  margin: 0;
+  padding: 0;
+
+  &%default-ul {
+    list-style-type: disc;
+    margin-bottom: $small-spacing;
+    padding-left: $base-spacing;
+  }
+
+  &%default-ol {
+    list-style-type: decimal;
+    margin-bottom: $small-spacing;
+    padding-left: $base-spacing;
+  }
+}
+
+dl {
+  margin-bottom: $small-spacing;
+
+  dt {
+    font-weight: bold;
+    margin-top: $small-spacing;
+  }
+
+  dd {
+    margin: 0;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_tables.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_tables.scss
new file mode 100644
index 00000000..61f527d5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_tables.scss
@@ -0,0 +1,25 @@
+table {
+  border-collapse: collapse;
+  font-feature-settings: "kern", "liga", "tnum";
+  margin: $small-spacing 0;
+  table-layout: fixed;
+  width: 100%;
+}
+
+th {
+  border-bottom: 1px solid shade($base-border-color, 25%);
+  font-weight: 600;
+  padding: $small-spacing 0;
+  text-align: left;
+}
+
+td {
+  border-bottom: $base-border;
+  padding: $small-spacing 0;
+}
+
+tr,
+td,
+th {
+  vertical-align: middle;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_typography.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_typography.scss
new file mode 100644
index 00000000..e60951db
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_typography.scss
@@ -0,0 +1,49 @@
+body {
+  color: $base-font-color;
+  font-family: $base-font-family;
+  font-feature-settings: "kern", "liga", "pnum";
+  font-size: $base-font-size;
+  line-height: $base-line-height;
+}
+
+h1,
+h2,
+h3,
+h4,
+h5,
+h6 {
+  font-family: $heading-font-family;
+  font-size: $base-font-size;
+  line-height: $heading-line-height;
+  margin: 0 0 $small-spacing;
+}
+
+p {
+  margin: 0 0 $small-spacing;
+}
+
+a {
+  color: $action-color;
+  text-decoration: none;
+  transition: color $base-duration $base-timing;
+
+  &:active,
+  &:focus,
+  &:hover {
+    color: shade($action-color, 25%);
+  }
+}
+
+hr {
+  border-bottom: $base-border;
+  border-left: 0;
+  border-right: 0;
+  border-top: 0;
+  margin: $base-spacing 0;
+}
+
+img,
+picture {
+  margin: 0;
+  max-width: 100%;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_variables.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_variables.scss
new file mode 100644
index 00000000..2a9d117a
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/base/_variables.scss
@@ -0,0 +1,42 @@
+// Typography
+$base-font-family: $helvetica;
+$heading-font-family: $base-font-family;
+
+// Font Sizes
+$base-font-size: 1em;
+
+// Line height
+$base-line-height: 1.5;
+$heading-line-height: 1.2;
+
+// Other Sizes
+$base-border-radius: 3px;
+$base-spacing: $base-line-height * 1em;
+$small-spacing: $base-spacing / 2;
+$base-z-index: 0;
+
+// Colors
+$blue: #477dca;
+$dark-gray: #333;
+$medium-gray: #999;
+$light-gray: #ddd;
+
+// Font Colors
+$base-font-color: $dark-gray;
+$action-color: $blue;
+
+// Border
+$base-border-color: $light-gray;
+$base-border: 1px solid $base-border-color;
+
+// Background Colors
+$base-background-color: #fff;
+$secondary-background-color: tint($base-border-color, 75%);
+
+// Forms
+$form-box-shadow: inset 0 1px 3px rgba(#000, 0.06);
+$form-box-shadow-focus: $form-box-shadow, 0 0 5px adjust-color($action-color, $lightness: -5%, $alpha: -0.3);
+
+// Animations
+$base-duration: 150ms;
+$base-timing: ease;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon-deprecated-upcoming.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon-deprecated-upcoming.scss
new file mode 100644
index 00000000..e6d1b8ce
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon-deprecated-upcoming.scss
@@ -0,0 +1,411 @@
+// The following features have been deprecated and will be removed in the next MAJOR version release
+
+@mixin inline-block {
+  display: inline-block;
+
+  @warn "The inline-block mixin is deprecated and will be removed in the next major version release";
+}
+
+@mixin button ($style: simple, $base-color: #4294f0, $text-size: inherit, $padding: 7px 18px) {
+
+  @if type-of($style) == string and type-of($base-color) == color {
+    @include buttonstyle($style, $base-color, $text-size, $padding);
+  }
+
+  @if type-of($style) == string and type-of($base-color) == number {
+    $padding: $text-size;
+    $text-size: $base-color;
+    $base-color: #4294f0;
+
+    @if $padding == inherit {
+      $padding: 7px 18px;
+    }
+
+    @include buttonstyle($style, $base-color, $text-size, $padding);
+  }
+
+  @if type-of($style) == color and type-of($base-color) == color {
+    $base-color: $style;
+    $style: simple;
+    @include buttonstyle($style, $base-color, $text-size, $padding);
+  }
+
+  @if type-of($style) == color and type-of($base-color) == number {
+    $padding: $text-size;
+    $text-size: $base-color;
+    $base-color: $style;
+    $style: simple;
+
+    @if $padding == inherit {
+      $padding: 7px 18px;
+    }
+
+    @include buttonstyle($style, $base-color, $text-size, $padding);
+  }
+
+  @if type-of($style) == number {
+    $padding: $base-color;
+    $text-size: $style;
+    $base-color: #4294f0;
+    $style: simple;
+
+    @if $padding == #4294f0 {
+      $padding: 7px 18px;
+    }
+
+    @include buttonstyle($style, $base-color, $text-size, $padding);
+  }
+
+  &:disabled {
+    cursor: not-allowed;
+    opacity: 0.5;
+  }
+
+  @warn "The button mixin is deprecated and will be removed in the next major version release";
+}
+
+// Selector Style Button
+@mixin buttonstyle($type, $b-color, $t-size, $pad) {
+  // Grayscale button
+  @if $type == simple and $b-color == grayscale($b-color) {
+    @include simple($b-color, true, $t-size, $pad);
+  }
+
+  @if $type == shiny and $b-color == grayscale($b-color) {
+    @include shiny($b-color, true, $t-size, $pad);
+  }
+
+  @if $type == pill and $b-color == grayscale($b-color) {
+    @include pill($b-color, true, $t-size, $pad);
+  }
+
+  @if $type == flat and $b-color == grayscale($b-color) {
+    @include flat($b-color, true, $t-size, $pad);
+  }
+
+  // Colored button
+  @if $type == simple {
+    @include simple($b-color, false, $t-size, $pad);
+  }
+
+  @else if $type == shiny {
+    @include shiny($b-color, false, $t-size, $pad);
+  }
+
+  @else if $type == pill {
+    @include pill($b-color, false, $t-size, $pad);
+  }
+
+  @else if $type == flat {
+    @include flat($b-color, false, $t-size, $pad);
+  }
+}
+
+// Simple Button
+@mixin simple($base-color, $grayscale: false, $textsize: inherit, $padding: 7px 18px) {
+  $color:         hsl(0, 0, 100%);
+  $border:        adjust-color($base-color, $saturation:  9%,  $lightness: -14%);
+  $inset-shadow:  adjust-color($base-color, $saturation: -8%,  $lightness:  15%);
+  $stop-gradient: adjust-color($base-color, $saturation:  9%,  $lightness: -11%);
+  $text-shadow:   adjust-color($base-color, $saturation:  15%, $lightness: -18%);
+
+  @if is-light($base-color) {
+    $color:       hsl(0, 0, 20%);
+    $text-shadow: adjust-color($base-color, $saturation: 10%, $lightness: 4%);
+  }
+
+  @if $grayscale == true {
+    $border:        grayscale($border);
+    $inset-shadow:  grayscale($inset-shadow);
+    $stop-gradient: grayscale($stop-gradient);
+    $text-shadow:   grayscale($text-shadow);
+  }
+
+  border: 1px solid $border;
+  border-radius: 3px;
+  box-shadow: inset 0 1px 0 0 $inset-shadow;
+  color: $color;
+  display: inline-block;
+  font-size: $textsize;
+  font-weight: bold;
+  @include linear-gradient ($base-color, $stop-gradient);
+  padding: $padding;
+  text-decoration: none;
+  text-shadow: 0 1px 0 $text-shadow;
+  background-clip: padding-box;
+
+  &:hover:not(:disabled) {
+    $base-color-hover:    adjust-color($base-color, $saturation: -4%, $lightness: -5%);
+    $inset-shadow-hover:  adjust-color($base-color, $saturation: -7%, $lightness:  5%);
+    $stop-gradient-hover: adjust-color($base-color, $saturation:  8%, $lightness: -14%);
+
+    @if $grayscale == true {
+      $base-color-hover:    grayscale($base-color-hover);
+      $inset-shadow-hover:  grayscale($inset-shadow-hover);
+      $stop-gradient-hover: grayscale($stop-gradient-hover);
+    }
+
+    @include linear-gradient ($base-color-hover, $stop-gradient-hover);
+
+    box-shadow: inset 0 1px 0 0 $inset-shadow-hover;
+    cursor: pointer;
+  }
+
+  &:active:not(:disabled),
+  &:focus:not(:disabled) {
+    $border-active:       adjust-color($base-color, $saturation: 9%, $lightness: -14%);
+    $inset-shadow-active: adjust-color($base-color, $saturation: 7%, $lightness: -17%);
+
+    @if $grayscale == true {
+      $border-active:       grayscale($border-active);
+      $inset-shadow-active: grayscale($inset-shadow-active);
+    }
+
+    border: 1px solid $border-active;
+    box-shadow: inset 0 0 8px 4px $inset-shadow-active, inset 0 0 8px 4px $inset-shadow-active;
+  }
+}
+
+// Shiny Button
+@mixin shiny($base-color, $grayscale: false, $textsize: inherit, $padding: 7px 18px) {
+  $color:         hsl(0, 0, 100%);
+  $border:        adjust-color($base-color, $red: -117, $green: -111, $blue: -81);
+  $border-bottom: adjust-color($base-color, $red: -126, $green: -127, $blue: -122);
+  $fourth-stop:   adjust-color($base-color, $red: -79,  $green: -70,  $blue: -46);
+  $inset-shadow:  adjust-color($base-color, $red:  37,  $green:  29,  $blue:  12);
+  $second-stop:   adjust-color($base-color, $red: -56,  $green: -50,  $blue: -33);
+  $text-shadow:   adjust-color($base-color, $red: -140, $green: -141, $blue: -114);
+  $third-stop:    adjust-color($base-color, $red: -86,  $green: -75,  $blue: -48);
+
+  @if is-light($base-color) {
+    $color:       hsl(0, 0, 20%);
+    $text-shadow: adjust-color($base-color, $saturation: 10%, $lightness: 4%);
+  }
+
+  @if $grayscale == true {
+    $border:        grayscale($border);
+    $border-bottom: grayscale($border-bottom);
+    $fourth-stop:   grayscale($fourth-stop);
+    $inset-shadow:  grayscale($inset-shadow);
+    $second-stop:   grayscale($second-stop);
+    $text-shadow:   grayscale($text-shadow);
+    $third-stop:    grayscale($third-stop);
+  }
+
+  @include linear-gradient(top, $base-color 0%, $second-stop 50%, $third-stop 50%, $fourth-stop 100%);
+
+  border: 1px solid $border;
+  border-bottom: 1px solid $border-bottom;
+  border-radius: 5px;
+  box-shadow: inset 0 1px 0 0 $inset-shadow;
+  color: $color;
+  display: inline-block;
+  font-size: $textsize;
+  font-weight: bold;
+  padding: $padding;
+  text-align: center;
+  text-decoration: none;
+  text-shadow: 0 -1px 1px $text-shadow;
+
+  &:hover:not(:disabled) {
+    $first-stop-hover:  adjust-color($base-color, $red: -13, $green: -15, $blue: -18);
+    $second-stop-hover: adjust-color($base-color, $red: -66, $green: -62, $blue: -51);
+    $third-stop-hover:  adjust-color($base-color, $red: -93, $green: -85, $blue: -66);
+    $fourth-stop-hover: adjust-color($base-color, $red: -86, $green: -80, $blue: -63);
+
+    @if $grayscale == true {
+      $first-stop-hover:  grayscale($first-stop-hover);
+      $second-stop-hover: grayscale($second-stop-hover);
+      $third-stop-hover:  grayscale($third-stop-hover);
+      $fourth-stop-hover: grayscale($fourth-stop-hover);
+    }
+
+    @include linear-gradient(top, $first-stop-hover  0%,
+                                  $second-stop-hover 50%,
+                                  $third-stop-hover  50%,
+                                  $fourth-stop-hover 100%);
+    cursor: pointer;
+  }
+
+  &:active:not(:disabled),
+  &:focus:not(:disabled) {
+    $inset-shadow-active: adjust-color($base-color, $red: -111, $green: -116, $blue: -122);
+
+    @if $grayscale == true {
+      $inset-shadow-active: grayscale($inset-shadow-active);
+    }
+
+    box-shadow: inset 0 0 20px 0 $inset-shadow-active;
+  }
+}
+
+// Pill Button
+@mixin pill($base-color, $grayscale: false, $textsize: inherit, $padding: 7px 18px) {
+  $color:         hsl(0, 0, 100%);
+  $border-bottom: adjust-color($base-color, $hue:  8, $saturation: -11%, $lightness: -26%);
+  $border-sides:  adjust-color($base-color, $hue:  4, $saturation: -21%, $lightness: -21%);
+  $border-top:    adjust-color($base-color, $hue: -1, $saturation: -30%, $lightness: -15%);
+  $inset-shadow:  adjust-color($base-color, $hue: -1, $saturation: -1%,  $lightness:  7%);
+  $stop-gradient: adjust-color($base-color, $hue:  8, $saturation:  14%, $lightness: -10%);
+  $text-shadow:   adjust-color($base-color, $hue:  5, $saturation: -19%, $lightness: -15%);
+
+  @if is-light($base-color) {
+    $color:       hsl(0, 0, 20%);
+    $text-shadow: adjust-color($base-color, $saturation: 10%, $lightness: 4%);
+  }
+
+  @if $grayscale == true {
+    $border-bottom: grayscale($border-bottom);
+    $border-sides:  grayscale($border-sides);
+    $border-top:    grayscale($border-top);
+    $inset-shadow:  grayscale($inset-shadow);
+    $stop-gradient: grayscale($stop-gradient);
+    $text-shadow:   grayscale($text-shadow);
+  }
+
+  border: 1px solid $border-top;
+  border-color: $border-top $border-sides $border-bottom;
+  border-radius: 16px;
+  box-shadow: inset 0 1px 0 0 $inset-shadow;
+  color: $color;
+  display: inline-block;
+  font-size: $textsize;
+  font-weight: normal;
+  line-height: 1;
+  @include linear-gradient ($base-color, $stop-gradient);
+  padding: $padding;
+  text-align: center;
+  text-decoration: none;
+  text-shadow: 0 -1px 1px $text-shadow;
+  background-clip: padding-box;
+
+  &:hover:not(:disabled) {
+    $base-color-hover:    adjust-color($base-color,                                $lightness: -4.5%);
+    $border-bottom:       adjust-color($base-color, $hue:  8, $saturation:  13.5%, $lightness: -32%);
+    $border-sides:        adjust-color($base-color, $hue:  4, $saturation: -2%,    $lightness: -27%);
+    $border-top:          adjust-color($base-color, $hue: -1, $saturation: -17%,   $lightness: -21%);
+    $inset-shadow-hover:  adjust-color($base-color,           $saturation: -1%,    $lightness:  3%);
+    $stop-gradient-hover: adjust-color($base-color, $hue:  8, $saturation: -4%,    $lightness: -15.5%);
+    $text-shadow-hover:   adjust-color($base-color, $hue:  5, $saturation: -5%,    $lightness: -22%);
+
+    @if $grayscale == true {
+      $base-color-hover:    grayscale($base-color-hover);
+      $border-bottom:       grayscale($border-bottom);
+      $border-sides:        grayscale($border-sides);
+      $border-top:          grayscale($border-top);
+      $inset-shadow-hover:  grayscale($inset-shadow-hover);
+      $stop-gradient-hover: grayscale($stop-gradient-hover);
+      $text-shadow-hover:   grayscale($text-shadow-hover);
+    }
+
+    @include linear-gradient ($base-color-hover, $stop-gradient-hover);
+
+    background-clip: padding-box;
+    border: 1px solid $border-top;
+    border-color: $border-top $border-sides $border-bottom;
+    box-shadow: inset 0 1px 0 0 $inset-shadow-hover;
+    cursor: pointer;
+    text-shadow: 0 -1px 1px $text-shadow-hover;
+  }
+
+  &:active:not(:disabled),
+  &:focus:not(:disabled) {
+    $active-color:         adjust-color($base-color, $hue: 4,  $saturation: -12%,  $lightness: -10%);
+    $border-active:        adjust-color($base-color, $hue: 6,  $saturation: -2.5%, $lightness: -30%);
+    $border-bottom-active: adjust-color($base-color, $hue: 11, $saturation:  6%,   $lightness: -31%);
+    $inset-shadow-active:  adjust-color($base-color, $hue: 9,  $saturation:  2%,   $lightness: -21.5%);
+    $text-shadow-active:   adjust-color($base-color, $hue: 5,  $saturation: -12%,  $lightness: -21.5%);
+
+    @if $grayscale == true {
+      $active-color:         grayscale($active-color);
+      $border-active:        grayscale($border-active);
+      $border-bottom-active: grayscale($border-bottom-active);
+      $inset-shadow-active:  grayscale($inset-shadow-active);
+      $text-shadow-active:   grayscale($text-shadow-active);
+    }
+
+    background: $active-color;
+    border: 1px solid $border-active;
+    border-bottom: 1px solid $border-bottom-active;
+    box-shadow: inset 0 0 6px 3px $inset-shadow-active;
+    text-shadow: 0 -1px 1px $text-shadow-active;
+  }
+}
+
+// Flat Button
+@mixin flat($base-color, $grayscale: false, $textsize: inherit, $padding: 7px 18px) {
+  $color:         hsl(0, 0, 100%);
+
+  @if is-light($base-color) {
+    $color:       hsl(0, 0, 20%);
+  }
+
+  background-color: $base-color;
+  border-radius: 3px;
+  border: 0;
+  color: $color;
+  display: inline-block;
+  font-size: $textsize;
+  font-weight: bold;
+  padding: $padding;
+  text-decoration: none;
+  background-clip: padding-box;
+
+  &:hover:not(:disabled){
+    $base-color-hover:    adjust-color($base-color, $saturation: 4%, $lightness: 5%);
+
+    @if $grayscale == true {
+      $base-color-hover: grayscale($base-color-hover);
+    }
+
+    background-color: $base-color-hover;
+    cursor: pointer;
+  }
+
+  &:active:not(:disabled),
+  &:focus:not(:disabled) {
+    $base-color-active: adjust-color($base-color, $saturation: -4%, $lightness: -5%);
+
+    @if $grayscale == true {
+      $base-color-active: grayscale($base-color-active);
+    }
+
+    background-color: $base-color-active;
+    cursor: pointer;
+  }
+}
+
+// Flexible grid
+@function flex-grid($columns, $container-columns: $fg-max-columns) {
+  $width: $columns * $fg-column + ($columns - 1) * $fg-gutter;
+  $container-width: $container-columns * $fg-column + ($container-columns - 1) * $fg-gutter;
+  @return percentage($width / $container-width);
+
+  @warn "The flex-grid function is deprecated and will be removed in the next major version release";
+}
+
+// Flexible gutter
+@function flex-gutter($container-columns: $fg-max-columns, $gutter: $fg-gutter) {
+  $container-width: $container-columns * $fg-column + ($container-columns - 1) * $fg-gutter;
+  @return percentage($gutter / $container-width);
+
+  @warn "The flex-gutter function is deprecated and will be removed in the next major version release";
+}
+
+@function grid-width($n) {
+  @return $n * $gw-column + ($n - 1) * $gw-gutter;
+
+  @warn "The grid-width function is deprecated and will be removed in the next major version release";
+}
+
+@function golden-ratio($value, $increment) {
+  @return modular-scale($increment, $value, $ratio: $golden);
+
+  @warn "The golden-ratio function is deprecated and will be removed in the next major version release. Please use the modular-scale function, instead.";
+}
+
+@mixin box-sizing($box) {
+  @include prefixer(box-sizing, $box, webkit moz spec);
+
+  @warn "The box-sizing mixin is deprecated and will be removed in the next major version release. This property can now be used un-prefixed.";
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon.scss
new file mode 100644
index 00000000..34b0cd47
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/_bourbon.scss
@@ -0,0 +1,87 @@
+// Bourbon 4.2.5
+// http://bourbon.io
+// Copyright 2011-2015 thoughtbot, inc.
+// MIT License
+
+@import "settings/prefixer";
+@import "settings/px-to-em";
+@import "settings/asset-pipeline";
+
+@import "functions/assign-inputs";
+@import "functions/contains";
+@import "functions/contains-falsy";
+@import "functions/is-length";
+@import "functions/is-light";
+@import "functions/is-number";
+@import "functions/is-size";
+@import "functions/px-to-em";
+@import "functions/px-to-rem";
+@import "functions/shade";
+@import "functions/strip-units";
+@import "functions/tint";
+@import "functions/transition-property-name";
+@import "functions/unpack";
+@import "functions/modular-scale";
+
+@import "helpers/convert-units";
+@import "helpers/directional-values";
+@import "helpers/font-source-declaration";
+@import "helpers/gradient-positions-parser";
+@import "helpers/linear-angle-parser";
+@import "helpers/linear-gradient-parser";
+@import "helpers/linear-positions-parser";
+@import "helpers/linear-side-corner-parser";
+@import "helpers/radial-arg-parser";
+@import "helpers/radial-positions-parser";
+@import "helpers/radial-gradient-parser";
+@import "helpers/render-gradients";
+@import "helpers/shape-size-stripper";
+@import "helpers/str-to-num";
+
+@import "css3/animation";
+@import "css3/appearance";
+@import "css3/backface-visibility";
+@import "css3/background";
+@import "css3/background-image";
+@import "css3/border-image";
+@import "css3/calc";
+@import "css3/columns";
+@import "css3/filter";
+@import "css3/flex-box";
+@import "css3/font-face";
+@import "css3/font-feature-settings";
+@import "css3/hidpi-media-query";
+@import "css3/hyphens";
+@import "css3/image-rendering";
+@import "css3/keyframes";
+@import "css3/linear-gradient";
+@import "css3/perspective";
+@import "css3/placeholder";
+@import "css3/radial-gradient";
+@import "css3/selection";
+@import "css3/text-decoration";
+@import "css3/transform";
+@import "css3/transition";
+@import "css3/user-select";
+
+@import "addons/border-color";
+@import "addons/border-radius";
+@import "addons/border-style";
+@import "addons/border-width";
+@import "addons/buttons";
+@import "addons/clearfix";
+@import "addons/ellipsis";
+@import "addons/font-stacks";
+@import "addons/hide-text";
+@import "addons/margin";
+@import "addons/padding";
+@import "addons/position";
+@import "addons/prefixer";
+@import "addons/retina-image";
+@import "addons/size";
+@import "addons/text-inputs";
+@import "addons/timing-functions";
+@import "addons/triangle";
+@import "addons/word-wrap";
+
+@import "bourbon-deprecated-upcoming";
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-color.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-color.scss
new file mode 100644
index 00000000..6f6ab36c
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-color.scss
@@ -0,0 +1,26 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `border-color` on specific sides of a box. Use a `null` value to “skip” a side.
+///
+/// @param {Arglist} $vals
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element {
+///     @include border-color(#a60b55 #76cd9c null #e8ae1a);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     border-left-color: #e8ae1a;
+///     border-right-color: #76cd9c;
+///     border-top-color: #a60b55;
+///   }
+///
+/// @require {mixin} directional-property
+///
+/// @output `border-color`
+
+@mixin border-color($vals...) {
+  @include directional-property(border, color, $vals...);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-radius.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-radius.scss
new file mode 100644
index 00000000..1f658633
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-radius.scss
@@ -0,0 +1,48 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `border-radius` on both corners on the side of a box.
+///
+/// @param {Number} $radii
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element-one {
+///     @include border-top-radius(5px);
+///   }
+///
+///   .element-two {
+///     @include border-left-radius(3px);
+///   }
+///
+/// @example css - CSS Output
+///   .element-one {
+///     border-top-left-radius: 5px;
+///     border-top-right-radius: 5px;
+///   }
+///
+///   .element-two {
+///     border-bottom-left-radius: 3px;
+///     border-top-left-radius: 3px;
+///   }
+///
+/// @output `border-radius`
+
+@mixin border-top-radius($radii) {
+  border-top-left-radius: $radii;
+  border-top-right-radius: $radii;
+}
+
+@mixin border-right-radius($radii) {
+  border-bottom-right-radius: $radii;
+  border-top-right-radius: $radii;
+}
+
+@mixin border-bottom-radius($radii) {
+  border-bottom-left-radius: $radii;
+  border-bottom-right-radius: $radii;
+}
+
+@mixin border-left-radius($radii) {
+  border-bottom-left-radius: $radii;
+  border-top-left-radius: $radii;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-style.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-style.scss
new file mode 100644
index 00000000..d86ee79d
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-style.scss
@@ -0,0 +1,25 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `border-style` on specific sides of a box. Use a `null` value to “skip” a side.
+///
+/// @param {Arglist} $vals
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element {
+///     @include border-style(dashed null solid);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     border-bottom-style: solid;
+///     border-top-style: dashed;
+///   }
+///
+/// @require {mixin} directional-property
+///
+/// @output `border-style`
+
+@mixin border-style($vals...) {
+  @include directional-property(border, style, $vals...);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-width.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-width.scss
new file mode 100644
index 00000000..0ea2d4b7
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_border-width.scss
@@ -0,0 +1,25 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `border-width` on specific sides of a box. Use a `null` value to “skip” a side.
+///
+/// @param {Arglist} $vals
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element {
+///     @include border-width(1em null 20px);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     border-bottom-width: 20px;
+///     border-top-width: 1em;
+///   }
+///
+/// @require {mixin} directional-property
+///
+/// @output `border-width`
+
+@mixin border-width($vals...) {
+  @include directional-property(border, width, $vals...);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_buttons.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_buttons.scss
new file mode 100644
index 00000000..debeabc5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_buttons.scss
@@ -0,0 +1,64 @@
+@charset "UTF-8";
+
+/// Generates variables for all buttons. Please note that you must use interpolation on the variable: `#{$all-buttons}`.
+///
+/// @example scss - Usage
+///   #{$all-buttons} {
+///     background-color: #f00;
+///   }
+///
+///   #{$all-buttons-focus},
+///   #{$all-buttons-hover} {
+///     background-color: #0f0;
+///   }
+///
+///   #{$all-buttons-active} {
+///     background-color: #00f;
+///   }
+///
+/// @example css - CSS Output
+///   button,
+///   input[type="button"],
+///   input[type="reset"],
+///   input[type="submit"] {
+///     background-color: #f00;
+///   }
+///
+///   button:focus,
+///   input[type="button"]:focus,
+///   input[type="reset"]:focus,
+///   input[type="submit"]:focus,
+///   button:hover,
+///   input[type="button"]:hover,
+///   input[type="reset"]:hover,
+///   input[type="submit"]:hover {
+///     background-color: #0f0;
+///   }
+///
+///   button:active,
+///   input[type="button"]:active,
+///   input[type="reset"]:active,
+///   input[type="submit"]:active {
+///     background-color: #00f;
+///   }
+///
+/// @require assign-inputs
+///
+/// @type List
+///
+/// @todo Remove double assigned variables (Lines 59–62) in v5.0.0
+
+$buttons-list: 'button',
+               'input[type="button"]',
+               'input[type="reset"]',
+               'input[type="submit"]';
+
+$all-buttons:        assign-inputs($buttons-list);
+$all-buttons-active: assign-inputs($buttons-list, active);
+$all-buttons-focus:  assign-inputs($buttons-list, focus);
+$all-buttons-hover:  assign-inputs($buttons-list, hover);
+
+$all-button-inputs:        $all-buttons;
+$all-button-inputs-active: $all-buttons-active;
+$all-button-inputs-focus:  $all-buttons-focus;
+$all-button-inputs-hover:  $all-buttons-hover;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_clearfix.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_clearfix.scss
new file mode 100644
index 00000000..11313d66
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_clearfix.scss
@@ -0,0 +1,25 @@
+@charset "UTF-8";
+
+/// Provides an easy way to include a clearfix for containing floats.
+///
+/// @link http://cssmojo.com/latest_new_clearfix_so_far/
+///
+/// @example scss - Usage
+///   .element {
+///     @include clearfix;
+///   }
+///
+/// @example css - CSS Output
+///   .element::after {
+///     clear: both;
+///     content: "";
+///     display: table;
+///   }
+
+@mixin clearfix {
+  &::after {
+    clear: both;
+    content: "";
+    display: table;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_ellipsis.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_ellipsis.scss
new file mode 100644
index 00000000..a367f651
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_ellipsis.scss
@@ -0,0 +1,30 @@
+@charset "UTF-8";
+
+/// Truncates text and adds an ellipsis to represent overflow.
+///
+/// @param {Number} $width [100%]
+///   Max-width for the string to respect before being truncated
+///
+/// @example scss - Usage
+///   .element {
+///     @include ellipsis;
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     display: inline-block;
+///     max-width: 100%;
+///     overflow: hidden;
+///     text-overflow: ellipsis;
+///     white-space: nowrap;
+///     word-wrap: normal;
+///   }
+
+@mixin ellipsis($width: 100%) {
+  display: inline-block;
+  max-width: $width;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  word-wrap: normal;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_font-stacks.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_font-stacks.scss
new file mode 100644
index 00000000..57128f42
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_font-stacks.scss
@@ -0,0 +1,31 @@
+@charset "UTF-8";
+
+/// Georgia font stack.
+///
+/// @type List
+
+$georgia: "Georgia", "Cambria", "Times New Roman", "Times", serif;
+
+/// Helvetica font stack.
+///
+/// @type List
+
+$helvetica: "Helvetica Neue", "Helvetica", "Roboto", "Arial", sans-serif;
+
+/// Lucida Grande font stack.
+///
+/// @type List
+
+$lucida-grande: "Lucida Grande", "Tahoma", "Verdana", "Arial", sans-serif;
+
+/// Monospace font stack.
+///
+/// @type List
+
+$monospace: "Bitstream Vera Sans Mono", "Consolas", "Courier", monospace;
+
+/// Verdana font stack.
+///
+/// @type List
+
+$verdana: "Verdana", "Geneva", sans-serif;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_hide-text.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_hide-text.scss
new file mode 100644
index 00000000..4caf20ed
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_hide-text.scss
@@ -0,0 +1,27 @@
+/// Hides the text in an element, commonly used to show an image. Some elements will need block-level styles applied.
+///
+/// @link http://zeldman.com/2012/03/01/replacing-the-9999px-hack-new-image-replacement
+///
+/// @example scss - Usage
+///   .element {
+///     @include hide-text;
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     overflow: hidden;
+///     text-indent: 101%;
+///     white-space: nowrap;
+///   }
+///
+/// @todo Remove height argument in v5.0.0
+
+@mixin hide-text($height: null) {
+  overflow: hidden;
+  text-indent: 101%;
+  white-space: nowrap;
+
+  @if $height {
+    @warn "The `hide-text` mixin has changed and no longer requires a height. The height argument will no longer be accepted in v5.0.0";
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_margin.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_margin.scss
new file mode 100644
index 00000000..674f4e5f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_margin.scss
@@ -0,0 +1,26 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `margin` on specific sides of a box. Use a `null` value to “skip” a side.
+///
+/// @param {Arglist} $vals
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element {
+///     @include margin(null 10px 3em 20vh);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     margin-bottom: 3em;
+///     margin-left: 20vh;
+///     margin-right: 10px;
+///   }
+///
+/// @require {mixin} directional-property
+///
+/// @output `margin`
+
+@mixin margin($vals...) {
+  @include directional-property(margin, false, $vals...);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_padding.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_padding.scss
new file mode 100644
index 00000000..40a5f006
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_padding.scss
@@ -0,0 +1,26 @@
+@charset "UTF-8";
+
+/// Provides a quick method for targeting `padding` on specific sides of a box. Use a `null` value to “skip” a side.
+///
+/// @param {Arglist} $vals
+///   List of arguments
+///
+/// @example scss - Usage
+///   .element {
+///     @include padding(12vh null 10px 5%);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     padding-bottom: 10px;
+///     padding-left: 5%;
+///     padding-top: 12vh;
+///   }
+///
+/// @require {mixin} directional-property
+///
+/// @output `padding`
+
+@mixin padding($vals...) {
+  @include directional-property(padding, false, $vals...);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_position.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_position.scss
new file mode 100644
index 00000000..e460f3ff
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_position.scss
@@ -0,0 +1,48 @@
+@charset "UTF-8";
+
+/// Provides a quick method for setting an element’s position. Use a `null` value to “skip” a side.
+///
+/// @param {Position} $position [relative]
+///   A CSS position value
+///
+/// @param {Arglist} $coordinates [null null null null]
+///   List of values that correspond to the 4-value syntax for the edges of a box
+///
+/// @example scss - Usage
+///   .element {
+///     @include position(absolute, 0 null null 10em);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     left: 10em;
+///     position: absolute;
+///     top: 0;
+///   }
+///
+/// @require {function} is-length
+/// @require {function} unpack
+
+@mixin position($position: relative, $coordinates: null null null null) {
+  @if type-of($position) == list {
+    $coordinates: $position;
+    $position: relative;
+  }
+
+  $coordinates: unpack($coordinates);
+
+  $offsets: (
+    top:    nth($coordinates, 1),
+    right:  nth($coordinates, 2),
+    bottom: nth($coordinates, 3),
+    left:   nth($coordinates, 4)
+  );
+
+  position: $position;
+
+  @each $offset, $value in $offsets {
+    @if is-length($value) {
+      #{$offset}: $value;
+    }
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_prefixer.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_prefixer.scss
new file mode 100644
index 00000000..2b6f7313
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_prefixer.scss
@@ -0,0 +1,66 @@
+@charset "UTF-8";
+
+/// A mixin for generating vendor prefixes on non-standardized properties.
+///
+/// @param {String} $property
+///   Property to prefix
+///
+/// @param {*} $value
+///   Value to use
+///
+/// @param {List} $prefixes
+///   Prefixes to define
+///
+/// @example scss - Usage
+///   .element {
+///     @include prefixer(border-radius, 10px, webkit ms spec);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     -webkit-border-radius: 10px;
+///     -moz-border-radius: 10px;
+///     border-radius: 10px;
+///   }
+///
+/// @require {variable} $prefix-for-webkit
+/// @require {variable} $prefix-for-mozilla
+/// @require {variable} $prefix-for-microsoft
+/// @require {variable} $prefix-for-opera
+/// @require {variable} $prefix-for-spec
+
+@mixin prefixer($property, $value, $prefixes) {
+  @each $prefix in $prefixes {
+    @if $prefix == webkit {
+      @if $prefix-for-webkit {
+        -webkit-#{$property}: $value;
+      }
+    } @else if $prefix == moz {
+      @if $prefix-for-mozilla {
+        -moz-#{$property}: $value;
+      }
+    } @else if $prefix == ms {
+      @if $prefix-for-microsoft {
+        -ms-#{$property}: $value;
+      }
+    } @else if $prefix == o {
+      @if $prefix-for-opera {
+        -o-#{$property}: $value;
+      }
+    } @else if $prefix == spec {
+      @if $prefix-for-spec {
+        #{$property}: $value;
+      }
+    } @else  {
+      @warn "Unrecognized prefix: #{$prefix}";
+    }
+  }
+}
+
+@mixin disable-prefix-for-all() {
+  $prefix-for-webkit:    false !global;
+  $prefix-for-mozilla:   false !global;
+  $prefix-for-microsoft: false !global;
+  $prefix-for-opera:     false !global;
+  $prefix-for-spec:      false !global;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_retina-image.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_retina-image.scss
new file mode 100644
index 00000000..7febbd75
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_retina-image.scss
@@ -0,0 +1,25 @@
+@mixin retina-image($filename, $background-size, $extension: png, $retina-filename: null, $retina-suffix: _2x, $asset-pipeline: $asset-pipeline) {
+  @if $asset-pipeline {
+    background-image: image-url("#{$filename}.#{$extension}");
+  } @else {
+    background-image:       url("#{$filename}.#{$extension}");
+  }
+
+  @include hidpi {
+    @if $asset-pipeline {
+      @if $retina-filename {
+        background-image: image-url("#{$retina-filename}.#{$extension}");
+      } @else {
+        background-image: image-url("#{$filename}#{$retina-suffix}.#{$extension}");
+      }
+    } @else {
+      @if $retina-filename {
+        background-image: url("#{$retina-filename}.#{$extension}");
+      } @else {
+        background-image: url("#{$filename}#{$retina-suffix}.#{$extension}");
+      }
+    }
+
+    background-size: $background-size;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_size.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_size.scss
new file mode 100644
index 00000000..a2992a34
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_size.scss
@@ -0,0 +1,51 @@
+@charset "UTF-8";
+
+/// Sets the `width` and `height` of the element.
+///
+/// @param {List} $size
+///   A list of at most 2 size values.
+///
+///   If there is only a single value in `$size` it is used for both width and height. All units are supported.
+///
+/// @example scss - Usage
+///   .first-element {
+///     @include size(2em);
+///   }
+///
+///   .second-element {
+///     @include size(auto 10em);
+///   }
+///
+/// @example css - CSS Output
+///   .first-element {
+///     width: 2em;
+///     height: 2em;
+///   }
+///
+///   .second-element {
+///     width: auto;
+///     height: 10em;
+///   }
+///
+/// @todo Refactor in 5.0.0 to use a comma-separated argument
+
+@mixin size($value) {
+  $width: nth($value, 1);
+  $height: $width;
+
+  @if length($value) > 1 {
+    $height: nth($value, 2);
+  }
+
+  @if is-size($height) {
+    height: $height;
+  } @else {
+    @warn "`#{$height}` is not a valid length for the `$height` parameter in the `size` mixin.";
+  }
+
+  @if is-size($width) {
+    width: $width;
+  } @else {
+    @warn "`#{$width}` is not a valid length for the `$width` parameter in the `size` mixin.";
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_text-inputs.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_text-inputs.scss
new file mode 100644
index 00000000..1eb7a545
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_text-inputs.scss
@@ -0,0 +1,113 @@
+@charset "UTF-8";
+
+/// Generates variables for all text-based inputs. Please note that you must use interpolation on the variable: `#{$all-text-inputs}`.
+///
+/// @example scss - Usage
+///   #{$all-text-inputs} {
+///     border: 1px solid #f00;
+///   }
+///
+///   #{$all-text-inputs-focus},
+///   #{$all-text-inputs-hover} {
+///     border: 1px solid #0f0;
+///   }
+///
+///   #{$all-text-inputs-active} {
+///     border: 1px solid #00f;
+///   }
+///
+/// @example css - CSS Output
+///   input[type="color"],
+///   input[type="date"],
+///   input[type="datetime"],
+///   input[type="datetime-local"],
+///   input[type="email"],
+///   input[type="month"],
+///   input[type="number"],
+///   input[type="password"],
+///   input[type="search"],
+///   input[type="tel"],
+///   input[type="text"],
+///   input[type="time"],
+///   input[type="url"],
+///   input[type="week"],
+///   textarea {
+///     border: 1px solid #f00;
+///   }
+///
+///   input[type="color"]:focus,
+///   input[type="date"]:focus,
+///   input[type="datetime"]:focus,
+///   input[type="datetime-local"]:focus,
+///   input[type="email"]:focus,
+///   input[type="month"]:focus,
+///   input[type="number"]:focus,
+///   input[type="password"]:focus,
+///   input[type="search"]:focus,
+///   input[type="tel"]:focus,
+///   input[type="text"]:focus,
+///   input[type="time"]:focus,
+///   input[type="url"]:focus,
+///   input[type="week"]:focus,
+///   textarea:focus,
+///   input[type="color"]:hover,
+///   input[type="date"]:hover,
+///   input[type="datetime"]:hover,
+///   input[type="datetime-local"]:hover,
+///   input[type="email"]:hover,
+///   input[type="month"]:hover,
+///   input[type="number"]:hover,
+///   input[type="password"]:hover,
+///   input[type="search"]:hover,
+///   input[type="tel"]:hover,
+///   input[type="text"]:hover,
+///   input[type="time"]:hover,
+///   input[type="url"]:hover,
+///   input[type="week"]:hover,
+///   textarea:hover {
+///     border: 1px solid #0f0;
+///   }
+///
+///   input[type="color"]:active,
+///   input[type="date"]:active,
+///   input[type="datetime"]:active,
+///   input[type="datetime-local"]:active,
+///   input[type="email"]:active,
+///   input[type="month"]:active,
+///   input[type="number"]:active,
+///   input[type="password"]:active,
+///   input[type="search"]:active,
+///   input[type="tel"]:active,
+///   input[type="text"]:active,
+///   input[type="time"]:active,
+///   input[type="url"]:active,
+///   input[type="week"]:active,
+///   textarea:active {
+///     border: 1px solid #00f;
+///   }
+///
+/// @require assign-inputs
+///
+/// @type List
+
+$text-inputs-list: 'input[type="color"]',
+                   'input[type="date"]',
+                   'input[type="datetime"]',
+                   'input[type="datetime-local"]',
+                   'input[type="email"]',
+                   'input[type="month"]',
+                   'input[type="number"]',
+                   'input[type="password"]',
+                   'input[type="search"]',
+                   'input[type="tel"]',
+                   'input[type="text"]',
+                   'input[type="time"]',
+                   'input[type="url"]',
+                   'input[type="week"]',
+                   'input:not([type])',
+                   'textarea';
+
+$all-text-inputs:        assign-inputs($text-inputs-list);
+$all-text-inputs-active: assign-inputs($text-inputs-list, active);
+$all-text-inputs-focus:  assign-inputs($text-inputs-list, focus);
+$all-text-inputs-hover:  assign-inputs($text-inputs-list, hover);
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_timing-functions.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_timing-functions.scss
new file mode 100644
index 00000000..20e5f1d4
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_timing-functions.scss
@@ -0,0 +1,34 @@
+@charset "UTF-8";
+
+/// CSS cubic-bezier timing functions. Timing functions courtesy of jquery.easie (github.com/jaukia/easie)
+///
+/// Timing functions are the same as demoed here: http://jqueryui.com/resources/demos/effect/easing.html
+///
+/// @type cubic-bezier
+
+$ease-in-quad:      cubic-bezier(0.550,  0.085, 0.680, 0.530);
+$ease-in-cubic:     cubic-bezier(0.550,  0.055, 0.675, 0.190);
+$ease-in-quart:     cubic-bezier(0.895,  0.030, 0.685, 0.220);
+$ease-in-quint:     cubic-bezier(0.755,  0.050, 0.855, 0.060);
+$ease-in-sine:      cubic-bezier(0.470,  0.000, 0.745, 0.715);
+$ease-in-expo:      cubic-bezier(0.950,  0.050, 0.795, 0.035);
+$ease-in-circ:      cubic-bezier(0.600,  0.040, 0.980, 0.335);
+$ease-in-back:      cubic-bezier(0.600, -0.280, 0.735, 0.045);
+
+$ease-out-quad:     cubic-bezier(0.250,  0.460, 0.450, 0.940);
+$ease-out-cubic:    cubic-bezier(0.215,  0.610, 0.355, 1.000);
+$ease-out-quart:    cubic-bezier(0.165,  0.840, 0.440, 1.000);
+$ease-out-quint:    cubic-bezier(0.230,  1.000, 0.320, 1.000);
+$ease-out-sine:     cubic-bezier(0.390,  0.575, 0.565, 1.000);
+$ease-out-expo:     cubic-bezier(0.190,  1.000, 0.220, 1.000);
+$ease-out-circ:     cubic-bezier(0.075,  0.820, 0.165, 1.000);
+$ease-out-back:     cubic-bezier(0.175,  0.885, 0.320, 1.275);
+
+$ease-in-out-quad:  cubic-bezier(0.455,  0.030, 0.515, 0.955);
+$ease-in-out-cubic: cubic-bezier(0.645,  0.045, 0.355, 1.000);
+$ease-in-out-quart: cubic-bezier(0.770,  0.000, 0.175, 1.000);
+$ease-in-out-quint: cubic-bezier(0.860,  0.000, 0.070, 1.000);
+$ease-in-out-sine:  cubic-bezier(0.445,  0.050, 0.550, 0.950);
+$ease-in-out-expo:  cubic-bezier(1.000,  0.000, 0.000, 1.000);
+$ease-in-out-circ:  cubic-bezier(0.785,  0.135, 0.150, 0.860);
+$ease-in-out-back:  cubic-bezier(0.680, -0.550, 0.265, 1.550);
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_triangle.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_triangle.scss
new file mode 100644
index 00000000..8a1ed9cd
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_triangle.scss
@@ -0,0 +1,63 @@
+@mixin triangle($size, $color, $direction) {
+  $width: nth($size, 1);
+  $height: nth($size, length($size));
+  $foreground-color: nth($color, 1);
+  $background-color: if(length($color) == 2, nth($color, 2), transparent);
+  height: 0;
+  width: 0;
+
+  @if ($direction == up) or ($direction == down) or ($direction == right) or ($direction == left) {
+    $width: $width / 2;
+    $height: if(length($size) > 1, $height, $height/2);
+
+    @if $direction == up {
+      border-bottom: $height solid $foreground-color;
+      border-left: $width solid $background-color;
+      border-right: $width solid $background-color;
+    } @else if $direction == right {
+      border-bottom: $width solid $background-color;
+      border-left: $height solid $foreground-color;
+      border-top: $width solid $background-color;
+    } @else if $direction == down {
+      border-left: $width solid $background-color;
+      border-right: $width solid $background-color;
+      border-top: $height solid $foreground-color;
+    } @else if $direction == left {
+      border-bottom: $width solid $background-color;
+      border-right: $height solid $foreground-color;
+      border-top: $width solid $background-color;
+    }
+  } @else if ($direction == up-right) or ($direction == up-left) {
+    border-top: $height solid $foreground-color;
+
+    @if $direction == up-right {
+      border-left:  $width solid $background-color;
+    } @else if $direction == up-left {
+      border-right: $width solid $background-color;
+    }
+  } @else if ($direction == down-right) or ($direction == down-left) {
+    border-bottom: $height solid $foreground-color;
+
+    @if $direction == down-right {
+      border-left:  $width solid $background-color;
+    } @else if $direction == down-left {
+      border-right: $width solid $background-color;
+    }
+  } @else if ($direction == inset-up) {
+    border-color: $background-color $background-color $foreground-color;
+    border-style: solid;
+    border-width: $height $width;
+  } @else if ($direction == inset-down) {
+    border-color: $foreground-color $background-color $background-color;
+    border-style: solid;
+    border-width: $height $width;
+  } @else if ($direction == inset-right) {
+    border-color: $background-color $background-color $background-color $foreground-color;
+    border-style: solid;
+    border-width: $width $height;
+  } @else if ($direction == inset-left) {
+    border-color: $background-color $foreground-color $background-color $background-color;
+    border-style: solid;
+    border-width: $width $height;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_word-wrap.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_word-wrap.scss
new file mode 100644
index 00000000..64856a92
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/addons/_word-wrap.scss
@@ -0,0 +1,29 @@
+@charset "UTF-8";
+
+/// Provides an easy way to change the `word-wrap` property.
+///
+/// @param {String} $wrap [break-word]
+///   Value for the `word-break` property.
+///
+/// @example scss - Usage
+///   .wrapper {
+///     @include word-wrap(break-word);
+///   }
+///
+/// @example css - CSS Output
+///   .wrapper {
+///     overflow-wrap: break-word;
+///     word-break: break-all;
+///     word-wrap: break-word;
+///   }
+
+@mixin word-wrap($wrap: break-word) {
+  overflow-wrap: $wrap;
+  word-wrap: $wrap;
+
+  @if $wrap == break-word {
+    word-break: break-all;
+  } @else {
+    word-break: $wrap;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_animation.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_animation.scss
new file mode 100644
index 00000000..aac675f5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_animation.scss
@@ -0,0 +1,43 @@
+// http://www.w3.org/TR/css3-animations/#the-animation-name-property-
+// Each of these mixins support comma separated lists of values, which allows different transitions for individual properties to be described in a single style rule. Each value in the list corresponds to the value at that same position in the other properties.
+
+@mixin animation($animations...) {
+  @include prefixer(animation, $animations, webkit moz spec);
+}
+
+@mixin animation-name($names...) {
+  @include prefixer(animation-name, $names, webkit moz spec);
+}
+
+@mixin animation-duration($times...) {
+  @include prefixer(animation-duration, $times, webkit moz spec);
+}
+
+@mixin animation-timing-function($motions...) {
+  // ease | linear | ease-in | ease-out | ease-in-out
+  @include prefixer(animation-timing-function, $motions, webkit moz spec);
+}
+
+@mixin animation-iteration-count($values...) {
+  // infinite | <number>
+  @include prefixer(animation-iteration-count, $values, webkit moz spec);
+}
+
+@mixin animation-direction($directions...) {
+  // normal | alternate
+  @include prefixer(animation-direction, $directions, webkit moz spec);
+}
+
+@mixin animation-play-state($states...) {
+  // running | paused
+  @include prefixer(animation-play-state, $states, webkit moz spec);
+}
+
+@mixin animation-delay($times...) {
+  @include prefixer(animation-delay, $times, webkit moz spec);
+}
+
+@mixin animation-fill-mode($modes...) {
+  // none | forwards | backwards | both
+  @include prefixer(animation-fill-mode, $modes, webkit moz spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_appearance.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_appearance.scss
new file mode 100644
index 00000000..abddc020
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_appearance.scss
@@ -0,0 +1,3 @@
+@mixin appearance($value) {
+  @include prefixer(appearance, $value, webkit moz ms o spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_backface-visibility.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_backface-visibility.scss
new file mode 100644
index 00000000..fc68e2dd
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_backface-visibility.scss
@@ -0,0 +1,3 @@
+@mixin backface-visibility($visibility) {
+  @include prefixer(backface-visibility, $visibility, webkit spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background-image.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background-image.scss
new file mode 100644
index 00000000..6ed19ab5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background-image.scss
@@ -0,0 +1,42 @@
+//************************************************************************//
+// Background-image property for adding multiple background images with
+// gradients, or for stringing multiple gradients together.
+//************************************************************************//
+
+@mixin background-image($images...) {
+  $webkit-images: ();
+  $spec-images: ();
+
+  @each $image in $images {
+    $webkit-image: ();
+    $spec-image: ();
+
+    @if (type-of($image) == string) {
+      $url-str:       str-slice($image, 1, 3);
+      $gradient-type: str-slice($image, 1, 6);
+
+      @if $url-str == "url" {
+        $webkit-image: $image;
+        $spec-image:   $image;
+      }
+
+      @else if $gradient-type == "linear" {
+        $gradients: _linear-gradient-parser($image);
+        $webkit-image:  map-get($gradients, webkit-image);
+        $spec-image:    map-get($gradients, spec-image);
+      }
+
+      @else if $gradient-type == "radial" {
+        $gradients: _radial-gradient-parser($image);
+        $webkit-image: map-get($gradients, webkit-image);
+        $spec-image:   map-get($gradients, spec-image);
+      }
+    }
+
+    $webkit-images: append($webkit-images, $webkit-image, comma);
+    $spec-images:   append($spec-images,   $spec-image,   comma);
+  }
+
+  background-image: $webkit-images;
+  background-image: $spec-images;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background.scss
new file mode 100644
index 00000000..019db0ed
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_background.scss
@@ -0,0 +1,55 @@
+//************************************************************************//
+// Background property for adding multiple backgrounds using shorthand
+// notation.
+//************************************************************************//
+
+@mixin background($backgrounds...) {
+  $webkit-backgrounds: ();
+  $spec-backgrounds: ();
+
+  @each $background in $backgrounds {
+    $webkit-background: ();
+    $spec-background: ();
+    $background-type: type-of($background);
+
+    @if $background-type == string or $background-type == list {
+      $background-str: if($background-type == list, nth($background, 1), $background);
+
+      $url-str:       str-slice($background-str, 1, 3);
+      $gradient-type: str-slice($background-str, 1, 6);
+
+      @if $url-str == "url" {
+        $webkit-background: $background;
+        $spec-background:   $background;
+      }
+
+      @else if $gradient-type == "linear" {
+        $gradients: _linear-gradient-parser("#{$background}");
+        $webkit-background: map-get($gradients, webkit-image);
+        $spec-background:   map-get($gradients, spec-image);
+      }
+
+      @else if $gradient-type == "radial" {
+        $gradients: _radial-gradient-parser("#{$background}");
+        $webkit-background: map-get($gradients, webkit-image);
+        $spec-background:   map-get($gradients, spec-image);
+      }
+
+      @else {
+        $webkit-background: $background;
+        $spec-background:   $background;
+      }
+    }
+
+    @else {
+      $webkit-background: $background;
+      $spec-background:   $background;
+    }
+
+    $webkit-backgrounds: append($webkit-backgrounds, $webkit-background, comma);
+    $spec-backgrounds:   append($spec-backgrounds,   $spec-background,   comma);
+  }
+
+  background: $webkit-backgrounds;
+  background: $spec-backgrounds;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_border-image.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_border-image.scss
new file mode 100644
index 00000000..cf568ce6
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_border-image.scss
@@ -0,0 +1,59 @@
+@mixin border-image($borders...) {
+  $webkit-borders: ();
+  $spec-borders: ();
+
+  @each $border in $borders {
+    $webkit-border: ();
+    $spec-border: ();
+    $border-type: type-of($border);
+
+    @if $border-type == string or list {
+      $border-str: if($border-type == list, nth($border, 1), $border);
+
+      $url-str:       str-slice($border-str, 1, 3);
+      $gradient-type: str-slice($border-str, 1, 6);
+
+      @if $url-str == "url" {
+        $webkit-border: $border;
+        $spec-border:   $border;
+      }
+
+      @else if $gradient-type == "linear" {
+        $gradients: _linear-gradient-parser("#{$border}");
+        $webkit-border: map-get($gradients, webkit-image);
+        $spec-border:   map-get($gradients, spec-image);
+      }
+
+      @else if $gradient-type == "radial" {
+        $gradients: _radial-gradient-parser("#{$border}");
+        $webkit-border: map-get($gradients, webkit-image);
+        $spec-border:   map-get($gradients, spec-image);
+      }
+
+      @else {
+        $webkit-border: $border;
+        $spec-border:   $border;
+      }
+    }
+
+    @else {
+      $webkit-border: $border;
+      $spec-border:   $border;
+    }
+
+    $webkit-borders: append($webkit-borders, $webkit-border, comma);
+    $spec-borders:   append($spec-borders,   $spec-border,   comma);
+  }
+
+  -webkit-border-image: $webkit-borders;
+          border-image: $spec-borders;
+          border-style: solid;
+}
+
+//Examples:
+// @include border-image(url("image.png"));
+// @include border-image(url("image.png") 20 stretch);
+// @include border-image(linear-gradient(45deg, orange, yellow));
+// @include border-image(linear-gradient(45deg, orange, yellow) stretch);
+// @include border-image(linear-gradient(45deg, orange, yellow) 20 30 40 50 stretch round);
+// @include border-image(radial-gradient(top, cover, orange, yellow, orange));
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_calc.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_calc.scss
new file mode 100644
index 00000000..0bfc738d
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_calc.scss
@@ -0,0 +1,4 @@
+@mixin calc($property, $value) {
+  #{$property}: -webkit-calc(#{$value});
+  #{$property}: calc(#{$value});
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_columns.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_columns.scss
new file mode 100644
index 00000000..96117670
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_columns.scss
@@ -0,0 +1,47 @@
+@mixin columns($arg: auto) {
+  // <column-count> || <column-width>
+  @include prefixer(columns, $arg, webkit moz spec);
+}
+
+@mixin column-count($int: auto) {
+  // auto || integer
+  @include prefixer(column-count, $int, webkit moz spec);
+}
+
+@mixin column-gap($length: normal) {
+  // normal || length
+  @include prefixer(column-gap, $length, webkit moz spec);
+}
+
+@mixin column-fill($arg: auto) {
+  // auto || length
+  @include prefixer(column-fill, $arg, webkit moz spec);
+}
+
+@mixin column-rule($arg) {
+  // <border-width> || <border-style> || <color>
+  @include prefixer(column-rule, $arg, webkit moz spec);
+}
+
+@mixin column-rule-color($color) {
+  @include prefixer(column-rule-color, $color, webkit moz spec);
+}
+
+@mixin column-rule-style($style: none) {
+  // none | hidden | dashed | dotted | double | groove | inset | inset | outset | ridge | solid
+  @include prefixer(column-rule-style, $style, webkit moz spec);
+}
+
+@mixin column-rule-width ($width: none) {
+  @include prefixer(column-rule-width, $width, webkit moz spec);
+}
+
+@mixin column-span($arg: none) {
+  // none || all
+  @include prefixer(column-span, $arg, webkit moz spec);
+}
+
+@mixin column-width($length: auto) {
+  // auto || length
+  @include prefixer(column-width, $length, webkit moz spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_filter.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_filter.scss
new file mode 100644
index 00000000..b8f8ffb0
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_filter.scss
@@ -0,0 +1,4 @@
+@mixin filter($function: none) {
+  // <filter-function> [<filter-function]* | none
+  @include prefixer(filter, $function, webkit spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_flex-box.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_flex-box.scss
new file mode 100644
index 00000000..0c9b1570
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_flex-box.scss
@@ -0,0 +1,287 @@
+// CSS3 Flexible Box Model and property defaults
+
+// Custom shorthand notation for flexbox
+@mixin box($orient: inline-axis, $pack: start, $align: stretch) {
+  @include display-box;
+  @include box-orient($orient);
+  @include box-pack($pack);
+  @include box-align($align);
+}
+
+@mixin display-box {
+  display: -webkit-box;
+  display: -moz-box;
+  display: -ms-flexbox; // IE 10
+  display: box;
+}
+
+@mixin box-orient($orient: inline-axis) {
+// horizontal|vertical|inline-axis|block-axis|inherit
+  @include prefixer(box-orient, $orient, webkit moz spec);
+}
+
+@mixin box-pack($pack: start) {
+// start|end|center|justify
+  @include prefixer(box-pack, $pack, webkit moz spec);
+  -ms-flex-pack: $pack; // IE 10
+}
+
+@mixin box-align($align: stretch) {
+// start|end|center|baseline|stretch
+  @include prefixer(box-align, $align, webkit moz spec);
+  -ms-flex-align: $align; // IE 10
+}
+
+@mixin box-direction($direction: normal) {
+// normal|reverse|inherit
+  @include prefixer(box-direction, $direction, webkit moz spec);
+  -ms-flex-direction: $direction; // IE 10
+}
+
+@mixin box-lines($lines: single) {
+// single|multiple
+  @include prefixer(box-lines, $lines, webkit moz spec);
+}
+
+@mixin box-ordinal-group($int: 1) {
+  @include prefixer(box-ordinal-group, $int, webkit moz spec);
+  -ms-flex-order: $int; // IE 10
+}
+
+@mixin box-flex($value: 0) {
+  @include prefixer(box-flex, $value, webkit moz spec);
+  -ms-flex: $value; // IE 10
+}
+
+@mixin box-flex-group($int: 1) {
+  @include prefixer(box-flex-group, $int, webkit moz spec);
+}
+
+// CSS3 Flexible Box Model and property defaults
+// Unified attributes for 2009, 2011, and 2012 flavours.
+
+// 2009 - display (box | inline-box)
+// 2011 - display (flexbox | inline-flexbox)
+// 2012 - display (flex | inline-flex)
+@mixin display($value) {
+// flex | inline-flex
+  @if $value == "flex" {
+    // 2009
+    display: -webkit-box;
+    display: -moz-box;
+    display: box;
+
+    // 2012
+    display: -webkit-flex;
+    display: -moz-flex;
+    display: -ms-flexbox; // 2011 (IE 10)
+    display: flex;
+  } @else if $value == "inline-flex" {
+    display: -webkit-inline-box;
+    display: -moz-inline-box;
+    display: inline-box;
+
+    display: -webkit-inline-flex;
+    display: -moz-inline-flex;
+    display: -ms-inline-flexbox;
+    display: inline-flex;
+  } @else {
+    display: $value;
+  }
+}
+
+// 2009 - box-flex (integer)
+// 2011 - flex (decimal | width decimal)
+// 2012 - flex (integer integer width)
+@mixin flex($value) {
+
+  // Grab flex-grow for older browsers.
+  $flex-grow: nth($value, 1);
+
+  // 2009
+  @include prefixer(box-flex, $flex-grow, webkit moz spec);
+
+  // 2011 (IE 10), 2012
+  @include prefixer(flex, $value, webkit moz ms spec);
+}
+
+// 2009 - box-orient ( horizontal | vertical | inline-axis | block-axis)
+//      - box-direction (normal | reverse)
+// 2011 - flex-direction (row | row-reverse | column | column-reverse)
+// 2012 - flex-direction (row | row-reverse | column | column-reverse)
+@mixin flex-direction($value: row) {
+
+  // Alt values.
+  $value-2009: $value;
+  $value-2011: $value;
+  $direction: normal;
+
+  @if $value == row {
+    $value-2009: horizontal;
+  } @else if $value == "row-reverse" {
+    $value-2009: horizontal;
+    $direction: reverse;
+  } @else if $value == column {
+    $value-2009: vertical;
+  } @else if $value == "column-reverse" {
+    $value-2009: vertical;
+    $direction: reverse;
+  }
+
+  // 2009
+  @include prefixer(box-orient, $value-2009, webkit moz spec);
+  @include prefixer(box-direction, $direction, webkit moz spec);
+
+  // 2012
+  @include prefixer(flex-direction, $value, webkit moz spec);
+
+  // 2011 (IE 10)
+  -ms-flex-direction: $value;
+}
+
+// 2009 - box-lines (single | multiple)
+// 2011 - flex-wrap (nowrap | wrap | wrap-reverse)
+// 2012 - flex-wrap (nowrap | wrap | wrap-reverse)
+@mixin flex-wrap($value: nowrap) {
+  // Alt values
+  $alt-value: $value;
+  @if $value == nowrap {
+    $alt-value: single;
+  } @else if $value == wrap {
+    $alt-value: multiple;
+  } @else if $value == "wrap-reverse" {
+    $alt-value: multiple;
+  }
+
+  @include prefixer(box-lines, $alt-value, webkit moz spec);
+  @include prefixer(flex-wrap, $value, webkit moz ms spec);
+}
+
+// 2009 - TODO: parse values into flex-direction/flex-wrap
+// 2011 - TODO: parse values into flex-direction/flex-wrap
+// 2012 - flex-flow (flex-direction || flex-wrap)
+@mixin flex-flow($value) {
+  @include prefixer(flex-flow, $value, webkit moz spec);
+}
+
+// 2009 - box-ordinal-group (integer)
+// 2011 - flex-order (integer)
+// 2012 - order (integer)
+@mixin order($int: 0) {
+  // 2009
+  @include prefixer(box-ordinal-group, $int, webkit moz spec);
+
+  // 2012
+  @include prefixer(order, $int, webkit moz spec);
+
+  // 2011 (IE 10)
+  -ms-flex-order: $int;
+}
+
+// 2012 - flex-grow (number)
+@mixin flex-grow($number: 0) {
+  @include prefixer(flex-grow, $number, webkit moz spec);
+  -ms-flex-positive: $number;
+}
+
+// 2012 - flex-shrink (number)
+@mixin flex-shrink($number: 1) {
+  @include prefixer(flex-shrink, $number, webkit moz spec);
+  -ms-flex-negative: $number;
+}
+
+// 2012 - flex-basis (number)
+@mixin flex-basis($width: auto) {
+  @include prefixer(flex-basis, $width, webkit moz spec);
+  -ms-flex-preferred-size: $width;
+}
+
+// 2009 - box-pack (start | end | center | justify)
+// 2011 - flex-pack (start | end | center | justify)
+// 2012 - justify-content (flex-start | flex-end | center | space-between | space-around)
+@mixin justify-content($value: flex-start) {
+
+  // Alt values.
+  $alt-value: $value;
+  @if $value == "flex-start" {
+    $alt-value: start;
+  } @else if $value == "flex-end" {
+    $alt-value: end;
+  } @else if $value == "space-between" {
+    $alt-value: justify;
+  } @else if $value == "space-around" {
+    $alt-value: distribute;
+  }
+
+  // 2009
+  @include prefixer(box-pack, $alt-value, webkit moz spec);
+
+  // 2012
+  @include prefixer(justify-content, $value, webkit moz ms o spec);
+
+  // 2011 (IE 10)
+  -ms-flex-pack: $alt-value;
+}
+
+// 2009 - box-align (start | end | center | baseline | stretch)
+// 2011 - flex-align (start | end | center | baseline | stretch)
+// 2012 - align-items (flex-start | flex-end | center | baseline | stretch)
+@mixin align-items($value: stretch) {
+
+  $alt-value: $value;
+
+  @if $value == "flex-start" {
+    $alt-value: start;
+  } @else if $value == "flex-end" {
+    $alt-value: end;
+  }
+
+  // 2009
+  @include prefixer(box-align, $alt-value, webkit moz spec);
+
+  // 2012
+  @include prefixer(align-items, $value, webkit moz ms o spec);
+
+  // 2011 (IE 10)
+  -ms-flex-align: $alt-value;
+}
+
+// 2011 - flex-item-align (auto | start | end | center | baseline | stretch)
+// 2012 - align-self (auto | flex-start | flex-end | center | baseline | stretch)
+@mixin align-self($value: auto) {
+
+  $value-2011: $value;
+  @if $value == "flex-start" {
+    $value-2011: start;
+  } @else if $value == "flex-end" {
+    $value-2011: end;
+  }
+
+  // 2012
+  @include prefixer(align-self, $value, webkit moz spec);
+
+  // 2011 (IE 10)
+  -ms-flex-item-align: $value-2011;
+}
+
+// 2011 - flex-line-pack (start | end | center | justify | distribute | stretch)
+// 2012 - align-content (flex-start | flex-end | center | space-between | space-around | stretch)
+@mixin align-content($value: stretch) {
+
+  $value-2011: $value;
+  @if $value == "flex-start" {
+    $value-2011: start;
+  } @else if $value == "flex-end" {
+    $value-2011: end;
+  } @else if $value == "space-between" {
+    $value-2011: justify;
+  } @else if $value == "space-around" {
+    $value-2011: distribute;
+  }
+
+  // 2012
+  @include prefixer(align-content, $value, webkit moz spec);
+
+  // 2011 (IE 10)
+  -ms-flex-line-pack: $value-2011;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-face.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-face.scss
new file mode 100644
index 00000000..a9fd1efc
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-face.scss
@@ -0,0 +1,24 @@
+@mixin font-face(
+  $font-family,
+  $file-path,
+  $weight: normal,
+  $style: normal,
+  $asset-pipeline: $asset-pipeline,
+  $file-formats: eot woff2 woff ttf svg) {
+
+  $font-url-prefix: font-url-prefixer($asset-pipeline);
+
+  @font-face {
+    font-family: $font-family;
+    font-style: $style;
+    font-weight: $weight;
+
+    src: font-source-declaration(
+      $font-family,
+      $file-path,
+      $asset-pipeline,
+      $file-formats,
+      $font-url-prefix
+    );
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-feature-settings.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-feature-settings.scss
new file mode 100644
index 00000000..9ac0452f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_font-feature-settings.scss
@@ -0,0 +1,4 @@
+@mixin font-feature-settings($settings...) {
+  @if length($settings) == 0 { $settings: none; }
+  @include prefixer(font-feature-settings, $settings, webkit moz ms spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hidpi-media-query.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hidpi-media-query.scss
new file mode 100644
index 00000000..c2825ea6
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hidpi-media-query.scss
@@ -0,0 +1,10 @@
+// HiDPI mixin. Default value set to 1.3 to target Google Nexus 7 (http://bjango.com/articles/min-device-pixel-ratio/)
+@mixin hidpi($ratio: 1.3) {
+  @media only screen and (-webkit-min-device-pixel-ratio: $ratio),
+  only screen and (min--moz-device-pixel-ratio: $ratio),
+  only screen and (-o-min-device-pixel-ratio: #{$ratio}/1),
+  only screen and (min-resolution: round($ratio * 96dpi)),
+  only screen and (min-resolution: $ratio * 1dppx) {
+    @content;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hyphens.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hyphens.scss
new file mode 100644
index 00000000..042f3471
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_hyphens.scss
@@ -0,0 +1,4 @@
+@mixin hyphens($hyphenation: none) {
+  // none | manual | auto
+  @include prefixer(hyphens, $hyphenation, webkit moz ms spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_image-rendering.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_image-rendering.scss
new file mode 100644
index 00000000..7e1a251c
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_image-rendering.scss
@@ -0,0 +1,14 @@
+@mixin image-rendering ($mode:auto) {
+
+  @if ($mode == crisp-edges) {
+    -ms-interpolation-mode: nearest-neighbor; // IE8+
+    image-rendering: -moz-crisp-edges;
+    image-rendering: -o-crisp-edges;
+    image-rendering: -webkit-optimize-contrast;
+    image-rendering: crisp-edges;
+  }
+
+  @else {
+    image-rendering: $mode;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_keyframes.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_keyframes.scss
new file mode 100644
index 00000000..cc22558f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_keyframes.scss
@@ -0,0 +1,36 @@
+// Adds keyframes blocks for supported prefixes, removing redundant prefixes in the block's content
+@mixin keyframes($name) {
+  $original-prefix-for-webkit:    $prefix-for-webkit;
+  $original-prefix-for-mozilla:   $prefix-for-mozilla;
+  $original-prefix-for-microsoft: $prefix-for-microsoft;
+  $original-prefix-for-opera:     $prefix-for-opera;
+  $original-prefix-for-spec:      $prefix-for-spec;
+
+  @if $original-prefix-for-webkit {
+    @include disable-prefix-for-all();
+    $prefix-for-webkit: true !global;
+    @-webkit-keyframes #{$name} {
+      @content;
+    }
+  }
+
+  @if $original-prefix-for-mozilla {
+    @include disable-prefix-for-all();
+    $prefix-for-mozilla: true !global;
+    @-moz-keyframes #{$name} {
+      @content;
+    }
+  }
+
+  $prefix-for-webkit:    $original-prefix-for-webkit    !global;
+  $prefix-for-mozilla:   $original-prefix-for-mozilla   !global;
+  $prefix-for-microsoft: $original-prefix-for-microsoft !global;
+  $prefix-for-opera:     $original-prefix-for-opera     !global;
+  $prefix-for-spec:      $original-prefix-for-spec      !global;
+
+  @if $original-prefix-for-spec {
+    @keyframes #{$name} {
+      @content;
+    }
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_linear-gradient.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_linear-gradient.scss
new file mode 100644
index 00000000..9e816333
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_linear-gradient.scss
@@ -0,0 +1,38 @@
+@mixin linear-gradient($pos, $g1, $g2: null,
+                       $g3: null, $g4: null,
+                       $g5: null, $g6: null,
+                       $g7: null, $g8: null,
+                       $g9: null, $g10: null,
+                       $fallback: null) {
+  // Detect what type of value exists in $pos
+  $pos-type: type-of(nth($pos, 1));
+  $pos-spec: null;
+  $pos-degree: null;
+
+  // If $pos is missing from mixin, reassign vars and add default position
+  @if ($pos-type == color) or (nth($pos, 1) == "transparent")  {
+    $g10: $g9; $g9: $g8; $g8: $g7; $g7: $g6; $g6: $g5;
+    $g5: $g4; $g4: $g3; $g3: $g2; $g2: $g1; $g1: $pos;
+    $pos: null;
+  }
+
+  @if $pos {
+    $positions: _linear-positions-parser($pos);
+    $pos-degree: nth($positions, 1);
+    $pos-spec:   nth($positions, 2);
+  }
+
+  $full: $g1, $g2, $g3, $g4, $g5, $g6, $g7, $g8, $g9, $g10;
+
+  // Set $g1 as the default fallback color
+  $fallback-color: nth($g1, 1);
+
+  // If $fallback is a color use that color as the fallback color
+  @if (type-of($fallback) == color) or ($fallback == "transparent") {
+    $fallback-color: $fallback;
+  }
+
+  background-color: $fallback-color;
+  background-image: -webkit-linear-gradient($pos-degree $full); // Safari 5.1+, Chrome
+  background-image: unquote("linear-gradient(#{$pos-spec}#{$full})");
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_perspective.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_perspective.scss
new file mode 100644
index 00000000..0e4deb80
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_perspective.scss
@@ -0,0 +1,8 @@
+@mixin perspective($depth: none) {
+  // none | <length>
+  @include prefixer(perspective, $depth, webkit moz spec);
+}
+
+@mixin perspective-origin($value: 50% 50%) {
+  @include prefixer(perspective-origin, $value, webkit moz spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_placeholder.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_placeholder.scss
new file mode 100644
index 00000000..5682fd09
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_placeholder.scss
@@ -0,0 +1,8 @@
+@mixin placeholder {
+  $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input";
+  @each $placeholder in $placeholders {
+    &:#{$placeholder}-placeholder {
+      @content;
+    }
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_radial-gradient.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_radial-gradient.scss
new file mode 100644
index 00000000..8da076e2
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_radial-gradient.scss
@@ -0,0 +1,39 @@
+// Requires Sass 3.1+
+@mixin radial-gradient($g1, $g2,
+                       $g3: null, $g4: null,
+                       $g5: null, $g6: null,
+                       $g7: null, $g8: null,
+                       $g9: null, $g10: null,
+                       $pos: null,
+                       $shape-size: null,
+                       $fallback: null) {
+
+  $data: _radial-arg-parser($g1, $g2, $pos, $shape-size);
+  $g1:  nth($data, 1);
+  $g2:  nth($data, 2);
+  $pos: nth($data, 3);
+  $shape-size: nth($data, 4);
+
+  $full: $g1, $g2, $g3, $g4, $g5, $g6, $g7, $g8, $g9, $g10;
+
+  // Strip deprecated cover/contain for spec
+  $shape-size-spec: _shape-size-stripper($shape-size);
+
+  // Set $g1 as the default fallback color
+  $first-color: nth($full, 1);
+  $fallback-color: nth($first-color, 1);
+
+  @if (type-of($fallback) == color) or ($fallback == "transparent") {
+    $fallback-color: $fallback;
+  }
+
+  // Add Commas and spaces
+  $shape-size: if($shape-size, "#{$shape-size}, ", null);
+  $pos:        if($pos, "#{$pos}, ", null);
+  $pos-spec:   if($pos, "at #{$pos}", null);
+  $shape-size-spec: if(($shape-size-spec != " ") and ($pos == null), "#{$shape-size-spec}, ", "#{$shape-size-spec} ");
+
+  background-color:  $fallback-color;
+  background-image: -webkit-radial-gradient(unquote(#{$pos}#{$shape-size}#{$full}));
+  background-image: unquote("radial-gradient(#{$shape-size-spec}#{$pos-spec}#{$full})");
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_selection.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_selection.scss
new file mode 100644
index 00000000..cd71d4f5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_selection.scss
@@ -0,0 +1,42 @@
+@charset "UTF-8";
+
+/// Outputs the spec and prefixed versions of the `::selection` pseudo-element.
+///
+/// @param {Bool} $current-selector [false]
+///   If set to `true`, it takes the current element into consideration.
+///
+/// @example scss - Usage
+///   .element {
+///     @include selection(true) {
+///       background-color: #ffbb52;
+///     }
+///   }
+///
+/// @example css - CSS Output
+///   .element::-moz-selection {
+///     background-color: #ffbb52;
+///   }
+///
+///   .element::selection {
+///     background-color: #ffbb52;
+///   }
+
+@mixin selection($current-selector: false) {
+  @if $current-selector {
+    &::-moz-selection {
+      @content;
+    }
+
+    &::selection {
+      @content;
+    }
+  } @else {
+    ::-moz-selection {
+      @content;
+    }
+
+    ::selection {
+      @content;
+    }
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_text-decoration.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_text-decoration.scss
new file mode 100644
index 00000000..9222746c
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_text-decoration.scss
@@ -0,0 +1,19 @@
+@mixin text-decoration($value) {
+// <text-decoration-line> || <text-decoration-style> || <text-decoration-color>
+  @include prefixer(text-decoration, $value, moz);
+}
+
+@mixin text-decoration-line($line: none) {
+// none || underline || overline || line-through
+  @include prefixer(text-decoration-line, $line, moz);
+}
+
+@mixin text-decoration-style($style: solid) {
+// solid || double || dotted || dashed || wavy
+  @include prefixer(text-decoration-style, $style, moz webkit);
+}
+
+@mixin text-decoration-color($color: currentColor) {
+// currentColor || <color>
+  @include prefixer(text-decoration-color, $color, moz);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transform.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transform.scss
new file mode 100644
index 00000000..8ee6509f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transform.scss
@@ -0,0 +1,15 @@
+@mixin transform($property: none) {
+  // none | <transform-function>
+  @include prefixer(transform, $property, webkit moz ms o spec);
+}
+
+@mixin transform-origin($axes: 50%) {
+  // x-axis - left | center | right  | length | %
+  // y-axis - top  | center | bottom | length | %
+  // z-axis -                          length
+  @include prefixer(transform-origin, $axes, webkit moz ms o spec);
+}
+
+@mixin transform-style($style: flat) {
+  @include prefixer(transform-style, $style, webkit moz ms o spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transition.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transition.scss
new file mode 100644
index 00000000..3c785ed5
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_transition.scss
@@ -0,0 +1,71 @@
+// Shorthand mixin. Supports multiple parentheses-deliminated values for each variable.
+// Example: @include transition (all 2s ease-in-out);
+//          @include transition (opacity 1s ease-in 2s, width 2s ease-out);
+//          @include transition-property (transform, opacity);
+
+@mixin transition($properties...) {
+  // Fix for vendor-prefix transform property
+  $needs-prefixes: false;
+  $webkit: ();
+  $moz: ();
+  $spec: ();
+
+  // Create lists for vendor-prefixed transform
+  @each $list in $properties {
+    @if nth($list, 1) == "transform" {
+      $needs-prefixes: true;
+      $list1: -webkit-transform;
+      $list2: -moz-transform;
+      $list3: ();
+
+      @each $var in $list {
+        $list3: join($list3, $var);
+
+        @if $var != "transform" {
+          $list1: join($list1, $var);
+          $list2: join($list2, $var);
+        }
+      }
+
+      $webkit: append($webkit, $list1);
+      $moz:    append($moz,    $list2);
+      $spec:   append($spec,   $list3);
+    } @else {
+      $webkit: append($webkit, $list, comma);
+      $moz:    append($moz,    $list, comma);
+      $spec:   append($spec,   $list, comma);
+    }
+  }
+
+  @if $needs-prefixes {
+    -webkit-transition: $webkit;
+       -moz-transition: $moz;
+            transition: $spec;
+  } @else {
+    @if length($properties) >= 1 {
+      @include prefixer(transition, $properties, webkit moz spec);
+    } @else {
+      $properties: all 0.15s ease-out 0s;
+      @include prefixer(transition, $properties, webkit moz spec);
+    }
+  }
+}
+
+@mixin transition-property($properties...) {
+  -webkit-transition-property: transition-property-names($properties, "webkit");
+     -moz-transition-property: transition-property-names($properties, "moz");
+          transition-property: transition-property-names($properties, false);
+}
+
+@mixin transition-duration($times...) {
+  @include prefixer(transition-duration, $times, webkit moz spec);
+}
+
+@mixin transition-timing-function($motions...) {
+  // ease | linear | ease-in | ease-out | ease-in-out | cubic-bezier()
+  @include prefixer(transition-timing-function, $motions, webkit moz spec);
+}
+
+@mixin transition-delay($times...) {
+  @include prefixer(transition-delay, $times, webkit moz spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_user-select.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_user-select.scss
new file mode 100644
index 00000000..d4e55510
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/css3/_user-select.scss
@@ -0,0 +1,3 @@
+@mixin user-select($value: none) {
+  @include prefixer(user-select, $value, webkit moz ms spec);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_assign-inputs.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_assign-inputs.scss
new file mode 100644
index 00000000..f8aba967
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_assign-inputs.scss
@@ -0,0 +1,11 @@
+@function assign-inputs($inputs, $pseudo: null) {
+  $list: ();
+
+  @each $input in $inputs {
+    $input: unquote($input);
+    $input: if($pseudo, $input + ":" + $pseudo, $input);
+    $list: append($list, $input, comma);
+  }
+
+  @return $list;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains-falsy.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains-falsy.scss
new file mode 100644
index 00000000..c096fdb9
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains-falsy.scss
@@ -0,0 +1,20 @@
+@charset "UTF-8";
+
+/// Checks if a list does not contains a value.
+///
+/// @access private
+///
+/// @param {List} $list
+///   The list to check against.
+///
+/// @return {Bool}
+
+@function contains-falsy($list) {
+  @each $item in $list {
+    @if not $item {
+      @return true;
+    }
+  }
+
+  @return false;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains.scss
new file mode 100644
index 00000000..3dec27db
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_contains.scss
@@ -0,0 +1,26 @@
+@charset "UTF-8";
+
+/// Checks if a list contains a value(s).
+///
+/// @access private
+///
+/// @param {List} $list
+///   The list to check against.
+///
+/// @param {List} $values
+///   A single value or list of values to check for.
+///
+/// @example scss - Usage
+///   contains($list, $value)
+///
+/// @return {Bool}
+
+@function contains($list, $values...) {
+  @each $value in $values {
+    @if type-of(index($list, $value)) != "number" {
+      @return false;
+    }
+  }
+
+  @return true;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-length.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-length.scss
new file mode 100644
index 00000000..5826e789
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-length.scss
@@ -0,0 +1,11 @@
+@charset "UTF-8";
+
+/// Checks for a valid CSS length.
+///
+/// @param {String} $value
+
+@function is-length($value) {
+  @return type-of($value) != "null" and (str-slice($value + "", 1, 4) == "calc"
+       or index(auto inherit initial 0, $value)
+       or (type-of($value) == "number" and not(unitless($value))));
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-light.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-light.scss
new file mode 100644
index 00000000..92d90ac3
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-light.scss
@@ -0,0 +1,21 @@
+@charset "UTF-8";
+
+/// Programatically determines whether a color is light or dark.
+///
+/// @link http://robots.thoughtbot.com/closer-look-color-lightness
+///
+/// @param {Color (Hex)} $color
+///
+/// @example scss - Usage
+///   is-light($color)
+///
+/// @return {Bool}
+
+@function is-light($hex-color) {
+  $-local-red: red(rgba($hex-color, 1));
+  $-local-green: green(rgba($hex-color, 1));
+  $-local-blue: blue(rgba($hex-color, 1));
+  $-local-lightness: ($-local-red * 0.2126 + $-local-green * 0.7152 + $-local-blue * 0.0722) / 255;
+
+  @return $-local-lightness > 0.6;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-number.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-number.scss
new file mode 100644
index 00000000..a64e0bf2
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-number.scss
@@ -0,0 +1,11 @@
+@charset "UTF-8";
+
+/// Checks for a valid number.
+///
+/// @param {Number} $value
+///
+/// @require {function} contains
+
+@function is-number($value) {
+  @return contains("0" "1" "2" "3" "4" "5" "6" "7" "8" "9" 0 1 2 3 4 5 6 7 8 9, $value);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-size.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-size.scss
new file mode 100644
index 00000000..661789ab
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_is-size.scss
@@ -0,0 +1,13 @@
+@charset "UTF-8";
+
+/// Checks for a valid CSS size.
+///
+/// @param {String} $value
+///
+/// @require {function} contains
+/// @require {function} is-length
+
+@function is-size($value) {
+  @return is-length($value)
+          or contains("fill" "fit-content" "min-content" "max-content", $value);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_modular-scale.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_modular-scale.scss
new file mode 100644
index 00000000..20fa3881
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_modular-scale.scss
@@ -0,0 +1,69 @@
+// Scaling Variables
+$golden:           1.618;
+$minor-second:     1.067;
+$major-second:     1.125;
+$minor-third:      1.2;
+$major-third:      1.25;
+$perfect-fourth:   1.333;
+$augmented-fourth: 1.414;
+$perfect-fifth:    1.5;
+$minor-sixth:      1.6;
+$major-sixth:      1.667;
+$minor-seventh:    1.778;
+$major-seventh:    1.875;
+$octave:           2;
+$major-tenth:      2.5;
+$major-eleventh:   2.667;
+$major-twelfth:    3;
+$double-octave:    4;
+
+$modular-scale-ratio: $perfect-fourth !default;
+$modular-scale-base: em($em-base) !default;
+
+@function modular-scale($increment, $value: $modular-scale-base, $ratio: $modular-scale-ratio) {
+  $v1: nth($value, 1);
+  $v2: nth($value, length($value));
+  $value: $v1;
+
+  // scale $v2 to just above $v1
+  @while $v2 > $v1 {
+    $v2: ($v2 / $ratio); // will be off-by-1
+  }
+  @while $v2 < $v1 {
+    $v2: ($v2 * $ratio); // will fix off-by-1
+  }
+
+  // check AFTER scaling $v2 to prevent double-counting corner-case
+  $double-stranded: $v2 > $v1;
+
+  @if $increment > 0 {
+    @for $i from 1 through $increment {
+      @if $double-stranded and ($v1 * $ratio) > $v2 {
+        $value: $v2;
+        $v2: ($v2 * $ratio);
+      } @else {
+        $v1: ($v1 * $ratio);
+        $value: $v1;
+      }
+    }
+  }
+
+  @if $increment < 0 {
+    // adjust $v2 to just below $v1
+    @if $double-stranded {
+      $v2: ($v2 / $ratio);
+    }
+
+    @for $i from $increment through -1 {
+      @if $double-stranded and ($v1 / $ratio) < $v2 {
+        $value: $v2;
+        $v2: ($v2 / $ratio);
+      } @else {
+        $v1: ($v1 / $ratio);
+        $value: $v1;
+      }
+    }
+  }
+
+  @return $value;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-em.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-em.scss
new file mode 100644
index 00000000..ae81a44a
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-em.scss
@@ -0,0 +1,13 @@
+// Convert pixels to ems
+// eg. for a relational value of 12px write em(12) when the parent is 16px
+// if the parent is another value say 24px write em(12, 24)
+
+@function em($pxval, $base: $em-base) {
+  @if not unitless($pxval) {
+    $pxval: strip-units($pxval);
+  }
+  @if not unitless($base) {
+    $base: strip-units($base);
+  }
+  @return ($pxval / $base) * 1em;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-rem.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-rem.scss
new file mode 100644
index 00000000..0ac941e7
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_px-to-rem.scss
@@ -0,0 +1,15 @@
+// Convert pixels to rems
+// eg. for a relational value of 12px write rem(12)
+// Assumes $em-base is the font-size of <html>
+
+@function rem($pxval) {
+  @if not unitless($pxval) {
+    $pxval: strip-units($pxval);
+  }
+
+  $base: $em-base;
+  @if not unitless($base) {
+    $base: strip-units($base);
+  }
+  @return ($pxval / $base) * 1rem;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_shade.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_shade.scss
new file mode 100644
index 00000000..8aaf2c6d
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_shade.scss
@@ -0,0 +1,24 @@
+@charset "UTF-8";
+
+/// Mixes a color with black.
+///
+/// @param {Color} $color
+///
+/// @param {Number (Percentage)} $percent
+///   The amount of black to be mixed in.
+///
+/// @example scss - Usage
+///   .element {
+///     background-color: shade(#ffbb52, 60%);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     background-color: #664a20;
+///   }
+///
+/// @return {Color}
+
+@function shade($color, $percent) {
+  @return mix(#000, $color, $percent);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_strip-units.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_strip-units.scss
new file mode 100644
index 00000000..6c5f3e81
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_strip-units.scss
@@ -0,0 +1,17 @@
+@charset "UTF-8";
+
+/// Strips the unit from a number.
+///
+/// @param {Number (With Unit)} $value
+///
+/// @example scss - Usage
+///   $dimension: strip-units(10em);
+///
+/// @example css - CSS Output
+///   $dimension: 10;
+///
+/// @return {Number (Unitless)}
+
+@function strip-units($value) {
+  @return ($value / ($value * 0 + 1));
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_tint.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_tint.scss
new file mode 100644
index 00000000..2e338148
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_tint.scss
@@ -0,0 +1,24 @@
+@charset "UTF-8";
+
+/// Mixes a color with white.
+///
+/// @param {Color} $color
+///
+/// @param {Number (Percentage)} $percent
+///   The amount of white to be mixed in.
+///
+/// @example scss - Usage
+///   .element {
+///     background-color: tint(#6ecaa6, 40%);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     background-color: #a8dfc9;
+///   }
+///
+/// @return {Color}
+
+@function tint($color, $percent) {
+  @return mix(#fff, $color, $percent);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_transition-property-name.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_transition-property-name.scss
new file mode 100644
index 00000000..18348b93
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_transition-property-name.scss
@@ -0,0 +1,22 @@
+// Return vendor-prefixed property names if appropriate
+// Example: transition-property-names((transform, color, background), moz) -> -moz-transform, color, background
+//************************************************************************//
+@function transition-property-names($props, $vendor: false) {
+  $new-props: ();
+
+  @each $prop in $props {
+    $new-props: append($new-props, transition-property-name($prop, $vendor), comma);
+  }
+
+  @return $new-props;
+}
+
+@function transition-property-name($prop, $vendor: false) {
+  // put other properties that need to be prefixed here aswell
+  @if $vendor and $prop == transform {
+    @return unquote('-'+$vendor+'-'+$prop);
+  }
+  @else {
+    @return $prop;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_unpack.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_unpack.scss
new file mode 100644
index 00000000..4367935d
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/functions/_unpack.scss
@@ -0,0 +1,27 @@
+@charset "UTF-8";
+
+/// Converts shorthand to the 4-value syntax.
+///
+/// @param {List} $shorthand
+///
+/// @example scss - Usage
+///   .element {
+///     margin: unpack(1em 2em);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     margin: 1em 2em 1em 2em;
+///   }
+
+@function unpack($shorthand) {
+  @if length($shorthand) == 1 {
+    @return nth($shorthand, 1) nth($shorthand, 1) nth($shorthand, 1) nth($shorthand, 1);
+  } @else if length($shorthand) == 2 {
+    @return nth($shorthand, 1) nth($shorthand, 2) nth($shorthand, 1) nth($shorthand, 2);
+  } @else if length($shorthand) == 3 {
+    @return nth($shorthand, 1) nth($shorthand, 2) nth($shorthand, 3) nth($shorthand, 2);
+  } @else {
+    @return $shorthand;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_convert-units.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_convert-units.scss
new file mode 100644
index 00000000..e0a65a05
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_convert-units.scss
@@ -0,0 +1,21 @@
+//************************************************************************//
+// Helper function for str-to-num fn.
+// Source: http://sassmeister.com/gist/9647408
+//************************************************************************//
+@function _convert-units($number, $unit) {
+  $strings: "px", "cm", "mm", "%", "ch", "pica", "in", "em", "rem", "pt", "pc", "ex", "vw", "vh", "vmin", "vmax", "deg", "rad", "grad", "turn";
+  $units:   1px, 1cm, 1mm, 1%, 1ch, 1pica, 1in, 1em, 1rem, 1pt, 1pc, 1ex, 1vw, 1vh, 1vmin, 1vmax, 1deg, 1rad, 1grad, 1turn;
+  $index: index($strings, $unit);
+
+  @if not $index {
+    @warn "Unknown unit `#{$unit}`.";
+    @return false;
+  }
+
+  @if type-of($number) != "number" {
+    @warn "`#{$number} is not a number`";
+    @return false;
+  }
+
+  @return $number * nth($units, $index);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_directional-values.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_directional-values.scss
new file mode 100644
index 00000000..6ee538db
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_directional-values.scss
@@ -0,0 +1,96 @@
+@charset "UTF-8";
+
+/// Directional-property mixins are shorthands for writing properties like the following
+///
+/// @ignore You can also use `false` instead of `null`.
+///
+/// @param {List} $vals
+///   List of directional values
+///
+/// @example scss - Usage
+///   .element {
+///     @include border-style(dotted null);
+///     @include margin(null 0 10px);
+///   }
+///
+/// @example css - CSS Output
+///   .element {
+///     border-bottom-style: dotted;
+///     border-top-style: dotted;
+///     margin-bottom: 10px;
+///     margin-left: 0;
+///     margin-right: 0;
+///   }
+///
+/// @require {function} contains-falsy
+///
+/// @return {List}
+
+@function collapse-directionals($vals) {
+  $output: null;
+
+  $a: nth($vals, 1);
+  $b: if(length($vals) < 2, $a, nth($vals, 2));
+  $c: if(length($vals) < 3, $a, nth($vals, 3));
+  $d: if(length($vals) < 2, $a, nth($vals, if(length($vals) < 4, 2, 4)));
+
+  @if $a == 0 { $a: 0; }
+  @if $b == 0 { $b: 0; }
+  @if $c == 0 { $c: 0; }
+  @if $d == 0 { $d: 0; }
+
+  @if $a == $b and $a == $c and $a == $d { $output: $a;          }
+  @else if $a == $c and $b == $d         { $output: $a $b;       }
+  @else if $b == $d                      { $output: $a $b $c;    }
+  @else                                  { $output: $a $b $c $d; }
+
+  @return $output;
+}
+
+/// Output directional properties, for instance `margin`.
+///
+/// @access private
+///
+/// @param {String} $pre
+///   Prefix to use
+/// @param {String} $suf
+///   Suffix to use
+/// @param {List} $vals
+///   List of values
+///
+/// @require {function} collapse-directionals
+/// @require {function} contains-falsy
+
+@mixin directional-property($pre, $suf, $vals) {
+  // Property Names
+  $top:    $pre + "-top"    + if($suf, "-#{$suf}", "");
+  $bottom: $pre + "-bottom" + if($suf, "-#{$suf}", "");
+  $left:   $pre + "-left"   + if($suf, "-#{$suf}", "");
+  $right:  $pre + "-right"  + if($suf, "-#{$suf}", "");
+  $all:    $pre +             if($suf, "-#{$suf}", "");
+
+  $vals: collapse-directionals($vals);
+
+  @if contains-falsy($vals) {
+    @if nth($vals, 1) { #{$top}: nth($vals, 1); }
+
+    @if length($vals) == 1 {
+      @if nth($vals, 1) { #{$right}: nth($vals, 1); }
+    } @else {
+      @if nth($vals, 2) { #{$right}: nth($vals, 2); }
+    }
+
+    @if length($vals) == 2 {
+      @if nth($vals, 1) { #{$bottom}: nth($vals, 1); }
+      @if nth($vals, 2) { #{$left}:   nth($vals, 2); }
+    } @else if length($vals) == 3 {
+      @if nth($vals, 3) { #{$bottom}: nth($vals, 3); }
+      @if nth($vals, 2) { #{$left}:   nth($vals, 2); }
+    } @else if length($vals) == 4 {
+      @if nth($vals, 3) { #{$bottom}: nth($vals, 3); }
+      @if nth($vals, 4) { #{$left}:   nth($vals, 4); }
+    }
+  } @else {
+    #{$all}: $vals;
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_font-source-declaration.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_font-source-declaration.scss
new file mode 100644
index 00000000..7f17586c
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_font-source-declaration.scss
@@ -0,0 +1,43 @@
+// Used for creating the source string for fonts using @font-face
+// Reference: http://goo.gl/Ru1bKP
+
+@function font-url-prefixer($asset-pipeline) {
+  @if $asset-pipeline == true {
+    @return font-url;
+  } @else {
+    @return url;
+  }
+}
+
+@function font-source-declaration(
+  $font-family,
+  $file-path,
+  $asset-pipeline,
+  $file-formats,
+  $font-url) {
+
+  $src: ();
+
+  $formats-map: (
+    eot:   "#{$file-path}.eot?#iefix" format("embedded-opentype"),
+    woff2: "#{$file-path}.woff2" format("woff2"),
+    woff:  "#{$file-path}.woff" format("woff"),
+    ttf:   "#{$file-path}.ttf" format("truetype"),
+    svg:   "#{$file-path}.svg##{$font-family}" format("svg")
+  );
+
+  @each $key, $values in $formats-map {
+    @if contains($file-formats, $key) {
+      $file-path: nth($values, 1);
+      $font-format: nth($values, 2);
+
+      @if $asset-pipeline == true {
+        $src: append($src, font-url($file-path) $font-format, comma);
+      } @else {
+        $src: append($src, url($file-path) $font-format, comma);
+      }
+    }
+  }
+
+  @return $src;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_gradient-positions-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_gradient-positions-parser.scss
new file mode 100644
index 00000000..07d30b6c
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_gradient-positions-parser.scss
@@ -0,0 +1,13 @@
+@function _gradient-positions-parser($gradient-type, $gradient-positions) {
+  @if $gradient-positions
+  and ($gradient-type == linear)
+  and (type-of($gradient-positions) != color) {
+    $gradient-positions: _linear-positions-parser($gradient-positions);
+  }
+  @else if $gradient-positions
+  and ($gradient-type == radial)
+  and (type-of($gradient-positions) != color) {
+    $gradient-positions: _radial-positions-parser($gradient-positions);
+  }
+  @return $gradient-positions;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-angle-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-angle-parser.scss
new file mode 100644
index 00000000..e0401ed8
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-angle-parser.scss
@@ -0,0 +1,25 @@
+// Private function for linear-gradient-parser
+@function _linear-angle-parser($image, $first-val, $prefix, $suffix) {
+  $offset: null;
+  $unit-short:  str-slice($first-val, str-length($first-val) - 2, str-length($first-val));
+  $unit-long:   str-slice($first-val, str-length($first-val) - 3, str-length($first-val));
+
+  @if ($unit-long == "grad") or
+      ($unit-long == "turn") {
+    $offset: if($unit-long == "grad", -100grad * 3, -0.75turn);
+  }
+
+  @else if ($unit-short == "deg") or
+           ($unit-short == "rad") {
+    $offset: if($unit-short == "deg", -90 * 3, 1.6rad);
+  }
+
+  @if $offset {
+    $num: _str-to-num($first-val);
+
+    @return (
+      webkit-image: -webkit- + $prefix + ($offset - $num) + $suffix,
+      spec-image: $image
+    );
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-gradient-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-gradient-parser.scss
new file mode 100644
index 00000000..48a8f77f
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-gradient-parser.scss
@@ -0,0 +1,41 @@
+@function _linear-gradient-parser($image) {
+  $image: unquote($image);
+  $gradients: ();
+  $start: str-index($image, "(");
+  $end: str-index($image, ",");
+  $first-val: str-slice($image, $start + 1, $end - 1);
+
+  $prefix: str-slice($image, 1, $start);
+  $suffix: str-slice($image, $end, str-length($image));
+
+  $has-multiple-vals: str-index($first-val, " ");
+  $has-single-position: unquote(_position-flipper($first-val) + "");
+  $has-angle: is-number(str-slice($first-val, 1, 1));
+
+  @if $has-multiple-vals {
+    $gradients: _linear-side-corner-parser($image, $first-val, $prefix, $suffix, $has-multiple-vals);
+  }
+
+  @else if $has-single-position != "" {
+    $pos: unquote($has-single-position + "");
+
+    $gradients: (
+      webkit-image: -webkit- + $image,
+      spec-image: $prefix + "to " + $pos + $suffix
+    );
+  }
+
+  @else if $has-angle {
+    // Rotate degree for webkit
+    $gradients: _linear-angle-parser($image, $first-val, $prefix, $suffix);
+  }
+
+  @else {
+    $gradients: (
+      webkit-image: -webkit- + $image,
+      spec-image: $image
+    );
+  }
+
+  @return $gradients;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-positions-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-positions-parser.scss
new file mode 100644
index 00000000..6d5cb6e1
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-positions-parser.scss
@@ -0,0 +1,61 @@
+@function _linear-positions-parser($pos) {
+  $type: type-of(nth($pos, 1));
+  $spec: null;
+  $degree: null;
+  $side: null;
+  $corner: null;
+  $length: length($pos);
+  // Parse Side and corner positions
+  @if ($length > 1) {
+    @if nth($pos, 1) == "to" { // Newer syntax
+      $side: nth($pos, 2);
+
+      @if $length == 2 { // eg. to top
+        // Swap for backwards compatability
+        $degree: _position-flipper(nth($pos, 2));
+      }
+      @else if $length == 3 { // eg. to top left
+        $corner: nth($pos, 3);
+      }
+    }
+    @else if $length == 2 { // Older syntax ("top left")
+      $side: _position-flipper(nth($pos, 1));
+      $corner: _position-flipper(nth($pos, 2));
+    }
+
+    @if ("#{$side} #{$corner}" == "left top") or ("#{$side} #{$corner}" == "top left") {
+      $degree: _position-flipper(#{$side}) _position-flipper(#{$corner});
+    }
+    @else if ("#{$side} #{$corner}" == "right top") or ("#{$side} #{$corner}" == "top right") {
+      $degree: _position-flipper(#{$side}) _position-flipper(#{$corner});
+    }
+    @else if ("#{$side} #{$corner}" == "right bottom") or ("#{$side} #{$corner}" == "bottom right") {
+      $degree: _position-flipper(#{$side}) _position-flipper(#{$corner});
+    }
+    @else if ("#{$side} #{$corner}" == "left bottom") or ("#{$side} #{$corner}" == "bottom left") {
+      $degree: _position-flipper(#{$side}) _position-flipper(#{$corner});
+    }
+    $spec: to $side $corner;
+  }
+  @else if $length == 1 {
+    // Swap for backwards compatability
+    @if $type == string {
+      $degree: $pos;
+      $spec: to _position-flipper($pos);
+    }
+    @else {
+      $degree: -270 - $pos; //rotate the gradient opposite from spec
+      $spec: $pos;
+    }
+  }
+  $degree: unquote($degree + ",");
+  $spec:   unquote($spec + ",");
+  @return $degree $spec;
+}
+
+@function _position-flipper($pos) {
+  @return if($pos == left, right, null)
+         if($pos == right, left, null)
+         if($pos == top, bottom, null)
+         if($pos == bottom, top, null);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-side-corner-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-side-corner-parser.scss
new file mode 100644
index 00000000..7a691253
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_linear-side-corner-parser.scss
@@ -0,0 +1,31 @@
+// Private function for linear-gradient-parser
+@function _linear-side-corner-parser($image, $first-val, $prefix, $suffix, $has-multiple-vals) {
+  $val-1: str-slice($first-val, 1, $has-multiple-vals - 1);
+  $val-2: str-slice($first-val, $has-multiple-vals + 1, str-length($first-val));
+  $val-3: null;
+  $has-val-3: str-index($val-2, " ");
+
+  @if $has-val-3 {
+    $val-3: str-slice($val-2, $has-val-3 + 1, str-length($val-2));
+    $val-2: str-slice($val-2, 1, $has-val-3 - 1);
+  }
+
+  $pos: _position-flipper($val-1) _position-flipper($val-2) _position-flipper($val-3);
+  $pos: unquote($pos + "");
+
+  // Use old spec for webkit
+  @if $val-1 == "to" {
+    @return (
+      webkit-image: -webkit- + $prefix + $pos + $suffix,
+      spec-image: $image
+    );
+  }
+
+  // Bring the code up to spec
+  @else {
+    @return (
+      webkit-image: -webkit- + $image,
+      spec-image: $prefix + "to " + $pos + $suffix
+    );
+  }
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-arg-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-arg-parser.scss
new file mode 100644
index 00000000..56c6030b
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-arg-parser.scss
@@ -0,0 +1,69 @@
+@function _radial-arg-parser($g1, $g2, $pos, $shape-size) {
+  @each $value in $g1, $g2 {
+    $first-val: nth($value, 1);
+    $pos-type:  type-of($first-val);
+    $spec-at-index: null;
+
+    // Determine if spec was passed to mixin
+    @if type-of($value) == list {
+      $spec-at-index: if(index($value, at), index($value, at), false);
+    }
+    @if $spec-at-index {
+      @if $spec-at-index > 1 {
+        @for $i from 1 through ($spec-at-index - 1) {
+          $shape-size: $shape-size nth($value, $i);
+        }
+        @for $i from ($spec-at-index + 1) through length($value) {
+          $pos: $pos nth($value, $i);
+        }
+      }
+      @else if $spec-at-index == 1 {
+        @for $i from ($spec-at-index + 1) through length($value) {
+          $pos: $pos nth($value, $i);
+        }
+      }
+      $g1: null;
+    }
+
+    // If not spec calculate correct values
+    @else {
+      @if ($pos-type != color) or ($first-val != "transparent") {
+        @if ($pos-type == number)
+        or ($first-val == "center")
+        or ($first-val == "top")
+        or ($first-val == "right")
+        or ($first-val == "bottom")
+        or ($first-val == "left") {
+
+          $pos: $value;
+
+          @if $pos == $g1 {
+            $g1: null;
+          }
+        }
+
+        @else if
+           ($first-val == "ellipse")
+        or ($first-val == "circle")
+        or ($first-val == "closest-side")
+        or ($first-val == "closest-corner")
+        or ($first-val == "farthest-side")
+        or ($first-val == "farthest-corner")
+        or ($first-val == "contain")
+        or ($first-val == "cover") {
+
+          $shape-size: $value;
+
+          @if $value == $g1 {
+            $g1: null;
+          }
+
+          @else if $value == $g2 {
+            $g2: null;
+          }
+        }
+      }
+    }
+  }
+  @return $g1, $g2, $pos, $shape-size;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-gradient-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-gradient-parser.scss
new file mode 100644
index 00000000..5444d808
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-gradient-parser.scss
@@ -0,0 +1,50 @@
+@function _radial-gradient-parser($image) {
+  $image: unquote($image);
+  $gradients: ();
+  $start: str-index($image, "(");
+  $end: str-index($image, ",");
+  $first-val: str-slice($image, $start + 1, $end - 1);
+
+  $prefix: str-slice($image, 1, $start);
+  $suffix: str-slice($image, $end, str-length($image));
+
+  $is-spec-syntax: str-index($first-val, "at");
+
+  @if $is-spec-syntax and $is-spec-syntax > 1 {
+    $keyword: str-slice($first-val, 1, $is-spec-syntax - 2);
+    $pos: str-slice($first-val, $is-spec-syntax + 3, str-length($first-val));
+    $pos: append($pos, $keyword, comma);
+
+    $gradients: (
+      webkit-image: -webkit- + $prefix + $pos + $suffix,
+      spec-image: $image
+    );
+  }
+
+  @else if $is-spec-syntax == 1 {
+    $pos: str-slice($first-val, $is-spec-syntax + 3, str-length($first-val));
+
+    $gradients: (
+      webkit-image: -webkit- + $prefix + $pos + $suffix,
+      spec-image: $image
+    );
+  }
+
+  @else if str-index($image, "cover") or str-index($image, "contain") {
+    @warn "Radial-gradient needs to be updated to conform to latest spec.";
+
+    $gradients: (
+      webkit-image: null,
+      spec-image: $image
+    );
+  }
+
+  @else {
+    $gradients: (
+      webkit-image: -webkit- + $image,
+      spec-image: $image
+    );
+  }
+
+  @return $gradients;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-positions-parser.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-positions-parser.scss
new file mode 100644
index 00000000..3c552ad7
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_radial-positions-parser.scss
@@ -0,0 +1,18 @@
+@function _radial-positions-parser($gradient-pos) {
+  $shape-size: nth($gradient-pos, 1);
+  $pos:        nth($gradient-pos, 2);
+  $shape-size-spec: _shape-size-stripper($shape-size);
+
+  $pre-spec: unquote(if($pos, "#{$pos}, ", null))
+             unquote(if($shape-size, "#{$shape-size},", null));
+  $pos-spec: if($pos, "at #{$pos}", null);
+
+  $spec: "#{$shape-size-spec} #{$pos-spec}";
+
+  // Add comma
+  @if ($spec != "  ") {
+    $spec: "#{$spec},";
+  }
+
+  @return $pre-spec $spec;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_render-gradients.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_render-gradients.scss
new file mode 100644
index 00000000..57656768
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_render-gradients.scss
@@ -0,0 +1,26 @@
+// User for linear and radial gradients within background-image or border-image properties
+
+@function _render-gradients($gradient-positions, $gradients, $gradient-type, $vendor: false) {
+  $pre-spec: null;
+  $spec: null;
+  $vendor-gradients: null;
+  @if $gradient-type == linear {
+    @if $gradient-positions {
+      $pre-spec: nth($gradient-positions, 1);
+      $spec:     nth($gradient-positions, 2);
+    }
+  }
+  @else if $gradient-type == radial {
+    $pre-spec: nth($gradient-positions, 1);
+    $spec:     nth($gradient-positions, 2);
+  }
+
+  @if $vendor {
+    $vendor-gradients: -#{$vendor}-#{$gradient-type}-gradient(#{$pre-spec} $gradients);
+  }
+  @else if $vendor == false {
+    $vendor-gradients: "#{$gradient-type}-gradient(#{$spec} #{$gradients})";
+    $vendor-gradients: unquote($vendor-gradients);
+  }
+  @return $vendor-gradients;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_shape-size-stripper.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_shape-size-stripper.scss
new file mode 100644
index 00000000..ee5eda42
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_shape-size-stripper.scss
@@ -0,0 +1,10 @@
+@function _shape-size-stripper($shape-size) {
+  $shape-size-spec: null;
+  @each $value in $shape-size {
+    @if ($value == "cover") or ($value == "contain") {
+      $value: null;
+    }
+    $shape-size-spec: "#{$shape-size-spec} #{$value}";
+  }
+  @return $shape-size-spec;
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_str-to-num.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_str-to-num.scss
new file mode 100644
index 00000000..3ef1d873
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/helpers/_str-to-num.scss
@@ -0,0 +1,50 @@
+//************************************************************************//
+// Helper function for linear/radial-gradient-parsers.
+// Source: http://sassmeister.com/gist/9647408
+//************************************************************************//
+@function _str-to-num($string) {
+  // Matrices
+  $strings: "0" "1" "2" "3" "4" "5" "6" "7" "8" "9";
+  $numbers:  0   1   2   3   4   5   6   7   8   9;
+
+  // Result
+  $result: 0;
+  $divider: 0;
+  $minus: false;
+
+  // Looping through all characters
+  @for $i from 1 through str-length($string) {
+    $character: str-slice($string, $i, $i);
+    $index: index($strings, $character);
+
+    @if $character == "-" {
+      $minus: true;
+    }
+
+    @else if $character == "." {
+      $divider: 1;
+    }
+
+    @else {
+      @if not $index {
+        $result: if($minus, $result * -1, $result);
+        @return _convert-units($result, str-slice($string, $i));
+      }
+
+      $number: nth($numbers, $index);
+
+      @if $divider == 0 {
+        $result: $result * 10;
+      }
+
+      @else {
+        // Move the decimal dot to the left
+        $divider: $divider * 10;
+        $number: $number / $divider;
+      }
+
+      $result: $result + $number;
+    }
+  }
+  @return if($minus, $result * -1, $result);
+}
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_asset-pipeline.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_asset-pipeline.scss
new file mode 100644
index 00000000..4c6afc5b
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_asset-pipeline.scss
@@ -0,0 +1,7 @@
+@charset "UTF-8";
+
+/// A global setting to enable or disable the `$asset-pipeline` variable for all functions that accept it.
+///
+/// @type Bool
+
+$asset-pipeline: false !default;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_prefixer.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_prefixer.scss
new file mode 100644
index 00000000..8c390514
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_prefixer.scss
@@ -0,0 +1,9 @@
+@charset "UTF-8";
+
+/// Global variables to enable or disable vendor prefixes
+
+$prefix-for-webkit:    true !default;
+$prefix-for-mozilla:   true !default;
+$prefix-for-microsoft: true !default;
+$prefix-for-opera:     true !default;
+$prefix-for-spec:      true !default;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_px-to-em.scss b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_px-to-em.scss
new file mode 100644
index 00000000..f2f9a3e8
--- /dev/null
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/bourbon/settings/_px-to-em.scss
@@ -0,0 +1 @@
+$em-base: 16px !default;
diff --git a/middleman-core/fixtures/minify-css-app/source/stylesheets/site.xcss.sass b/middleman-core/fixtures/minify-css-app/source/stylesheets/site.xcss.sass
index 0cf9e7da..7e4fa8ca 100755
--- a/middleman-core/fixtures/minify-css-app/source/stylesheets/site.xcss.sass
+++ b/middleman-core/fixtures/minify-css-app/source/stylesheets/site.xcss.sass
@@ -1,5 +1,6 @@
-@import "compass/reset"
+@import "bourbon/bourbon";
+@import "base/base";
 
 @media handheld, only screen and (device-width: 768px)
   body
-    display: block
\ No newline at end of file
+    display: block
diff --git a/middleman-core/lib/middleman-core/renderers/sass.rb b/middleman-core/lib/middleman-core/renderers/sass.rb
index ff449f4b..dcbe0bf3 100644
--- a/middleman-core/lib/middleman-core/renderers/sass.rb
+++ b/middleman-core/lib/middleman-core/renderers/sass.rb
@@ -1,33 +1,10 @@
 require 'sass'
-require 'compass/import-once'
 
-GLOB = /\*|\[.+\]/
-
-# Hack around broken sass globs when combined with import-once
-# Targets compass-import-once 1.0.4
-# Tracking issue: https://github.com/chriseppstein/compass/issues/1529
-module Compass
-  module ImportOnce
-    module Importer
-      def find_relative(uri, base, options, *args)
-        if uri =~ GLOB
-          force_import = true
-        else
-          uri, force_import = handle_force_import(uri)
-        end
-        maybe_replace_with_dummy_engine(super(uri, base, options, *args), options, force_import)
-      end
-
-      def find(uri, options, *args)
-        if uri =~ GLOB
-          force_import = true
-        else
-          uri, force_import = handle_force_import(uri)
-        end
-        maybe_replace_with_dummy_engine(super(uri, options, *args), options, force_import)
-      end
-    end
-  end
+SASS_MODULE = begin
+  require 'sassc'
+  ::SassC
+rescue LoadError => e
+  ::Sass
 end
 
 module Middleman
@@ -47,6 +24,7 @@ module Middleman
         app.config.define_setting :sass, opts, 'Sass engine options'
 
         app.config.define_setting :sass_assets_paths, [], 'Paths to extra SASS/SCSS files'
+        app.config.define_setting :sass_source_maps, app.development?, 'Whether to inline sourcemap into Sass'
 
         # Tell Tilt to use it as well (for inline sass blocks)
         ::Tilt.register 'sass', SassPlusCSSFilenameTemplate
@@ -56,8 +34,6 @@ module Middleman
         ::Tilt.register 'scss', ScssPlusCSSFilenameTemplate
         ::Tilt.prefer(ScssPlusCSSFilenameTemplate)
 
-        ::Compass::ImportOnce.activate!
-
         require 'middleman-core/renderers/sass_functions'
       end
 
@@ -82,11 +58,12 @@ module Middleman
         # @return [String]
         def evaluate(context, _)
           @context ||= context
-          @engine = ::Sass::Engine.new(data, sass_options)
+
+          @engine = SASS_MODULE::Engine.new(data, sass_options)
 
           begin
             @engine.render
-          rescue ::Sass::SyntaxError => e
+          rescue SASS_MODULE::SyntaxError => e
             ::Sass::SyntaxError.exception_to_css(e)
           end
         end
@@ -104,6 +81,12 @@ module Middleman
             custom: (options[:custom] || {}).merge(middleman_context: ctx.app)
           }
 
+          if ctx.config[:sass_source_maps]
+            more_opts[:source_map_file] = "."
+            more_opts[:source_map_embed] = true
+            more_opts[:source_map_contents] = true
+          end
+
           if ctx.is_a?(::Middleman::TemplateContext) && file
             more_opts[:css_filename] = file.sub(/\.s[ac]ss$/, '')
           end
diff --git a/middleman-core/lib/middleman-core/renderers/sass_functions.rb b/middleman-core/lib/middleman-core/renderers/sass_functions.rb
index 90583aee..a28dcc69 100644
--- a/middleman-core/lib/middleman-core/renderers/sass_functions.rb
+++ b/middleman-core/lib/middleman-core/renderers/sass_functions.rb
@@ -1,4 +1,4 @@
-module Sprockets
+module Middleman
   module Sass
     module Functions
       # Using Middleman::Util#asset_path, return the full path
@@ -92,25 +92,25 @@ module Sprockets
   end
 end
 
-module Sass::Script::Functions
-  include Sprockets::Sass::Functions
+module ::Sass::Script::Functions
+  include ::Middleman::Sass::Functions
 
-  # Hack to ensure previous API declarations (by Compass or whatever)
-  # don't take precedence.
-  [:asset_path, :asset_url, :image_path, :image_url, :font_path, :font_url, :asset_data_uri].each do |method|
-    defined?(@signatures) && @signatures.delete(method)
-  end
+  # # Hack to ensure previous API declarations (by Compass or whatever)
+  # # don't take precedence.
+  # [:asset_path, :asset_url, :image_path, :image_url, :font_path, :font_url, :asset_data_uri].each do |method|
+  #   defined?(@signatures) && @signatures.delete(method)
+  # end
 
-  declare :asset_path,     [:source], var_kwargs: true
-  declare :asset_path,     [:source, :kind]
-  declare :asset_url,      [:source], var_kwargs: true
-  declare :asset_url,      [:source, :kind]
-  declare :image_path,     [:source], var_kwargs: true
-  declare :image_url,      [:source], var_kwargs: true
-  declare :image_url,      [:source, :only_path]
-  declare :image_url,      [:source, :only_path, :cache_buster]
-  declare :font_path,      [:source], var_kwargs: true
-  declare :font_url,       [:source], var_kwargs: true
-  declare :font_url,       [:source, :only_path]
-  declare :asset_data_uri, [:source]
+  # declare :asset_path,     [:source], var_kwargs: true
+  # declare :asset_path,     [:source, :kind]
+  # declare :asset_url,      [:source], var_kwargs: true
+  # declare :asset_url,      [:source, :kind]
+  # declare :image_path,     [:source], var_kwargs: true
+  # declare :image_url,      [:source], var_kwargs: true
+  # declare :image_url,      [:source, :only_path]
+  # declare :image_url,      [:source, :only_path, :cache_buster]
+  # declare :font_path,      [:source], var_kwargs: true
+  # declare :font_url,       [:source], var_kwargs: true
+  # declare :font_url,       [:source, :only_path]
+  # declare :asset_data_uri, [:source]
 end
diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index eb747036..4f5738b3 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -25,7 +25,7 @@ Gem::Specification.new do |s|
   s.add_dependency('erubis')
 
   # Helpers
-  s.add_dependency('activesupport', ['~> 4.2.0'])
+  s.add_dependency('activesupport', ['~> 4.2'])
   s.add_dependency('padrino-helpers', ['~> 0.12.3'])
   s.add_dependency("addressable", ["~> 2.3.5"])
 
@@ -42,17 +42,14 @@ Gem::Specification.new do |s|
   s.add_dependency('fastimage', ['~> 1.6.2'])
 
   # Minify CSS
-  s.add_dependency('sass', ['>= 3.3.4'])
-
-  # Work around Sass performance
-  s.add_dependency('compass-import-once', ['~> 1.0.4'])
+  s.add_dependency('sassc', ['>= 1.6.0'])
 
   # Minify JS
   s.add_dependency('uglifier', ['~> 2.6'])
   s.add_dependency('execjs', ['~> 2.0'])
 
   # Testing
-  s.add_dependency('contracts', ['~> 0.11.0'])
+  s.add_dependency('contracts', ['~> 0.12.0'])
 
   # Hash stuff
   s.add_dependency('hashie', ['~> 3.4'])