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;

  display: flex;
  flex-direction: row;
  align-items: stretch;

  > li {
    display: flex;
    margin-right: 0.5em;

    > a,
    button {
      border: none;
      border-radius: var(--d-nav-pill-border-radius);
      padding: 6px 12px;
      color: var(--primary);
      font-size: var(--font-up-1);
      line-height: var(--line-height-small);
      box-sizing: border-box;
      min-height: 30px;
      display: flex;
      align-items: center;
      transition: background-color 0.2s, color 0.2s;

      .d-icon {
        margin-right: 5px;
        opacity: 0.65;
      }

      &:hover {
        color: var(--quaternary);
        background-color: var(--quaternary-low);
      }
    }

    a.active,
    button.active {
      color: var(--secondary);
      background-color: var(--quaternary);

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

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

.nav-stacked {
  @extend %nav;
  padding: 0;
  background: var(--primary-low);

  li {
    border-bottom: 1px solid var(--primary-low-mid-or-secondary-high);

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

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

  a {
    margin: 0;
    padding: 0.75em;
    font-size: var(--font-up-1);
    line-height: var(--line-height-small);
    cursor: pointer;
    color: var(--primary);
    @include ellipsis;

    &.active {
      color: var(--secondary);
      background-color: var(--quaternary);
      position: relative;

      --arrow-thickness: 8px;

      &::after {
        position: absolute;
        right: 0;
        top: calc(50% - var(--arrow-thickness));
        content: " ";
        border: var(--arrow-thickness) solid transparent;
        border-left-color: var(--secondary);
      }
    }
  }

  .count {
    font-size: var(--font-down-1);
  }

  .glyph {
    font-size: var(--font-down-1);
    width: 1.25em;
    text-align: center;
    margin-right: 0.25em;
    line-height: var(--line-height-large);
  }
}