gitlabhq/app/assets/stylesheets/sections/themes.scss

.application-theme, .code-preview-theme {
  .update-feedback {
    color: #468847;
    float: right;
  }
}

.themes_opts {
  padding-left: 20px;

  label {
    width: 175px;
    margin-right: 40px;

    .prev {
      @extend .thumbnail;
      height: 30px;
      width: 175px;
      margin-bottom: 10px;

      &.classic {
        background: #31363e;
      }

      &.default {
        background: #f1f1f1;
      }

      &.modern {
        background: #567;
      }

      &.gray {
        background: #708090;
      }

      &.violet {
        background: #657;
      }
    }
  }
}

.code_highlight_opts {
  padding-left: 20px;

  label {
    width: 220px;
    margin-right: 40px;

    .prev {
      @extend .thumbnail;
      height: 151px;
      width: 220px;
      margin-bottom: 10px;
    }
  }
}