edx-platform/xmodule/css/sequence/display.scss

$seq-nav-border-color: $border-color !default;
$seq-nav-hover-color: rgb(245, 245, 245) !default;
$seq-nav-link-color: $link-color !default;
$seq-nav-icon-color: rgb(10, 10, 10) !default;
$seq-nav-icon-color-muted: rgb(90, 90, 90) !default;
$seq-nav-tooltip-color: rgb(51, 51, 51) !default;
$seq-nav-height: 50px;

// repeated extends - needed since LMS styling was referenced
.block-link {
  @include border-left(1px solid $seq-nav-border-color);

  display: block;

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

.topbar {
  @include clearfix();

  border-bottom: 1px solid $seq-nav-border-color;

  @media print {
    display: none;
  }

  a {
    &.block-link {
      @include border-left(1px solid $seq-nav-border-color);

      display: block;

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

%ui-clear-button {
  background-color: transparent;
  background-image: none;
  background-position: center 14px;
  background-repeat: no-repeat;
  border: none;
  border-radius: 0;
  background-clip: border-box;
  box-shadow: none;
  box-sizing: content-box;
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
}


// ====================

.sequence-nav {
  @extend .topbar;

  margin: 0 auto $baseline;
  position: relative;
  border-bottom: none;
  z-index: 0;
  height: $seq-nav-height;
  display: flex;
  justify-content: center;

  @media print {
    display: none;
  }

  .sequence-list-wrapper {
    @extend %ui-depth2;

    position: relative;
    height: 100%;
    flex-grow: 1;

    @include media-breakpoint-down(xs) {
      white-space: nowrap;
      overflow-x: scroll;
    }
  }

  ol {
    display: flex;

    li {
      box-sizing: border-box;
      min-width: 40px;
      flex-grow: 1;
      border-color: $seq-nav-border-color;
      border-width: 1px;
      border-top-style: solid;

      &:not(:last-child) {
        @include border-right-style(solid);
      }

      button {
        @extend %ui-fake-link;
        @extend %ui-clear-button;

        width: 100%;
        height: ($seq-nav-height - 1);
        position: relative;
        margin: 0;
        padding: 0;
        display: block;
        text-align: center;
        border-color: $seq-nav-border-color;
        border-width: 1px;
        border-bottom-style: solid;
        box-sizing: border-box;
        overflow: visible; // for tooltip - IE11 uses 'hidden' by default if width/height is specified

        .icon {
          display: inline-block;
          line-height: 100%; // This matches the height of the <a> its within (the parent) to get vertical centering.
          font-size: 110%;
          color: $seq-nav-icon-color-muted;
        }

        .fa-bookmark {
          color: $seq-nav-link-color;
        }

        //video
        &.seq_video {
          .icon::before {
            content: "\f008"; // .fa-film
          }
        }

        //other
        &.seq_other {
          .icon::before {
            content: "\f02d"; // .fa-book
          }
        }

        //vertical
        &.seq_vertical {
          .icon::before {
            content: "\f00b";  // .fa-tasks
          }
        }

        //problems
        &.seq_problem {
          .icon::before {
            content: "\f044";  // .fa-pencil-square-o
          }
        }

        .sequence-tooltip {
          @include text-align(left);

          @extend %ui-depth2;

          margin-top: 12px;
          background: $seq-nav-tooltip-color;
          color: $white;
          font-family: $font-family-sans-serif;
          line-height: lh();
          right: 0;  // Should not be RTLed, tooltips do not move in RTL
          padding: 6px;
          position: absolute;
          top: 48px;
          text-shadow: 0 -1px 0 $black;
          white-space: pre;
          pointer-events: none;

          &:empty {
            background: none;

            &::after {
              display: none;
            }
          }

          &::after {
            @include transform(rotate(45deg));
            @include right(18px);

            background: $seq-nav-tooltip-color;
            content: " ";
            display: block;
            height: 10px;
            right: 18px;  // Not RTLed, positions tooltips relative to seq nav item
            position: absolute;
            top: -5px;
            width: 10px;
          }
        }
      }
    }
  }

  body.touch-based-device & ol li button:hover p {
    display: none;
  }
}

.sequence-nav-button {
  @extend %ui-depth3;

  display: block;
  top: 0;
  min-width: 40px;
  max-width: 40px;
  height: 100%;
  text-shadow: none; // overrides default button text-shadow
  background: none;  // overrides default button gradient
  background-color: theme-color("inverse");
  border-color: $seq-nav-border-color;
  box-shadow: none;
  font-size: inherit;
  font-weight: normal;
  padding: 0;
  white-space: nowrap;
  overflow-x: hidden;

  @include media-breakpoint-up(md) {
    min-width: 120px;
    max-width: 200px;
    text-overflow: ellipsis;

    span:not(:last-child) {
      @include padding-right($baseline / 2);
    }
  }

  .sequence-nav-button-label {
    display: none;

    @include media-breakpoint-up(md) {
      display: inline;
    }
  }

  &.button-previous {
    order: -999;

    @include media-breakpoint-up(md) {
      @include left(0);
      @include border-top-left-radius(3px);
      @include border-top-right-radius(0);
      @include border-bottom-right-radius(0);
      @include border-bottom-left-radius(3px);
    }
  }

  &.button-next {
    order: 999;

    @include media-breakpoint-up(md) {
      @include right(0);
      @include border-top-left-radius(0);
      @include border-top-right-radius(3px);
      @include border-bottom-right-radius(3px);
      @include border-bottom-left-radius(0);
    }
  }

  &.disabled {
    cursor: normal;
  }
}

.seq_contents {
  display: none;
}

.sequence-bottom {
  position: relative;
  height: 45px;
  margin: lh(2) auto;
  display: flex;
  justify-content: center;

  .sequence-nav-button {
    position: relative;
    min-width: 120px;
    max-width: 200px;
    text-overflow: ellipsis;

    &:last-of-type {
      @include border-left(none);
    }
  }

  @media print {
    display: none;
  }
}

#seq_content {
  &:focus,
  &:active {
    outline: none;
  }
}

// hover and active states
.sequence-nav-button,
.sequence-nav button {
  &.focused,
  &:hover,
  &:active,
  &.active {
    padding-top: 2px;
    background-color: theme-color("primary");

    .icon {
      color: theme-color("inverse");
    }

    @include media-breakpoint-up(sm) {
      border-bottom: 3px solid $seq-nav-link-color;
      background-color: theme-color("inverse");

      .icon {
        color: $seq-nav-icon-color;
      }
    }
  }
}