discourse/app/assets/stylesheets/common/components/navs.scss

// --------------------------------------------------
// Navigation menus
// --------------------------------------------------

// Base
// --------------------------------------------------

%nav {
  margin-left: 0;
  list-style: none;
  li a {
    display: block;
    text-decoration: none;
  }
}

// Pill nav
// --------------------------------------------------

.nav-pills {
  @extend %nav;
  @extend .clearfix;

  > li {
    float: left;
    margin-right: 5px;

    > a {
      border: none;
      padding: 6px 12px;
      color: $primary;
      font-size: $font-up-1;
      line-height: $line-height-medium;
      transition: background .15s;

      .d-icon {
        margin-right: 5px;
        opacity: .65;
      }

      &:hover {
        color: $quaternary;
        background-color: $quaternary-low;
      }
    }

    &.active > a,
    > a.active {
      color: $secondary;
      background-color: $quaternary;

      .d-icon {
        opacity: 1;
      }
    }
  }
}

// Stacked nav
// --------------------------------------------------

.nav-stacked {
  @extend %nav;
  padding: 0;
  overflow: hidden;
  background: $primary-low;

  li {
    border-bottom: 1px solid $primary-low;
    position: relative;

    &:last-of-type {
      border-bottom: 0;
    }

    &.indent {
      padding-left: 15px;
    }
  }

  a {
    margin: 0;
    padding: 13px;
    font-size: $font-up-1;
    line-height: $line-height-small;
    cursor: pointer;
    color: $primary;

    &.active {
      color: $secondary;
      background-color: $quaternary;

      &::after {
        left: 90%;
        top: 33%;
        content: " ";
        position: absolute;
        border: 8px solid transparent;
        border-left-color: $secondary;
      }
    }
  }

  .count {
    font-size: $font-down-1;
    line-height: $line-height-large;
  }

  .glyph {
    font-size: $font-down-1;
    width: 1.25em;
    text-align: center;
    margin-right: .5em;
    line-height: $line-height-large;
  }
}