edx-platform/lms/static/sass/course/base/_extends.scss

h1.top-header {
  border-bottom: 1px solid $border-color-2;
  text-align: left;
  font-size: em(24);
  font-weight: 100;
  padding-bottom: lh();
}

.button-reset {
  text-transform: none;
  letter-spacing: 0;

  &:hover, &:focus {
    text-decoration: none;
  }
}

.light-button, a.light-button, // only used in askbot as classes
.gray-button {
  @include button(simple, #eee);
  @extend .button-reset;
  font-size: em(13);
}

.blue-button {
  @include button(simple, $blue);
  @extend .button-reset;
  font-size: em(13);
}

.pink-button {
  @include button(simple, $pink);
  @extend .button-reset;
  font-size: em(13);
}

.content {
  @include box-sizing(border-box);
  display: table-cell;
  padding: 2em 2.5em;
  vertical-align: top;
  width: flex-grid(9) + flex-gutter();

  @media print {
    box-shadow: none;
  }
}

.sidebar {
  @include box-sizing(border-box);
  display: table-cell;
  font-family: $sans-serif;
  font-size: 14px;
  position: relative;
  vertical-align: top;
  width: flex-grid(3);
  background: $sidebar-color;

  h1, h2 {
   font-size: em(20);
   font-weight: bold;
   letter-spacing: 0;
   text-transform: none;
   font-family: $sans-serif;
   text-align: left;
   font-style: normal;
  }

  h1 {
    font-size: 18px;
    padding: 32px 26px 20px 26px;
  }

  a {
    border: none;
    font-style: normal;
  }

  .bottom-border {
    border-bottom: 1px solid $border-color;
  }

  @media print {
    display: none;
  }

  h3 {
    background: none;
    border: none;
    color: #000;
    font-weight: normal;
    margin: 0;
    overflow: hidden;
    font-size: 1em;

    a {
      display: block;
      text-decoration: none;
      @include transition(none);
    }

    &.active {
      // @extend .bottom-border;
      color: #000;
      font-weight: bold;

      a {
        color: #000;
      }
    }
  }

  ul, ol {
    list-style: none;
    margin: 0;
    padding-left: 0;

    li {
      // @extend .bottom-border;
      @extend .clearfix;
      background: none;
      position: relative;
      padding: 0;

      a {
        display: block;
        line-height: lh();
        font-size: 1em;
        @include box-sizing(border-box);
        padding: lh(.25) lh(.5) lh(.25) 0;

        &:hover, &:focus {
          color: #666;
          background: #f6f6f6;
        }
      }
    }
  }

  header#open_close_accordion {
    position: relative;

    a {
      background: #f6f6f6 url('../images/slide-left-icon.png') center center no-repeat;
      border: 1px solid #D3D3D3;
      border-radius: 3px 0 0 3px;
      height: 16px;
      padding: 6px;
      position: absolute;
      right: -1px;
      text-indent: -9999px;
      top: 12px;
      width: 16px;
      z-index: 99;

      &:hover, &:focus {
        background-color: white;
      }
    }
  }

  a.button {
    text-decoration: none;
  }
}

.topbar {
  @extend .clearfix;
  border-bottom: 1px solid $border-color;

  @media print {
    display: none;
  }

  a {
    &.block-link {
      border-left: 1px solid lighten($border-color, 10%);
      display: block;

      &:hover, &:focus {
        background: none;
      }
    }
  }
}

.tran {
  @include transition( all .2s $ease-in-out-quad 0s);
}