gentelella/vendors/select2/docs/_sass/_sidenav.scss

// Side navigation
//
// Scrollspy and affixed enhanced navigation to
// highlight sections and secondary sections of docs content`.

.s2-docs-sidebar {
  // By default it is not affixed in mobile views, so undo that
  &.affix {
    position: static;
  }

  @media (min-width: 768px) {
    padding-left: 20px;
  }
}

// First level of nav
.s2-docs-sidenav {
  margin-top: 20px;
  margin-bottom: 20px;
}

// All levels of nav
.s2-docs-sidebar .nav {
  > li > a {
    margin-left: -1px;
    display: block;
    padding: 4px 20px;
    font-size: 13px;
    font-weight: 500;
    color: #767676;
    border-left: 1px solid transparent;
    transition: color .2s, border-color .2s;
  }

  > li > a code {
    background-color: inherit;
    color: inherit;
  }

  > li > a:hover,
  > li > a:focus {
    color: #428BCA;
    text-decoration: none;
    background-color: transparent;
    border-left-color: #428BCA;
  }

  > .active > a,
  > .active:hover > a,
  > .active:focus > a {
    padding-left: 19px;
    font-weight: bold;
    color: #428BCA;
    background-color: transparent;
    border-left: 2px solid #428BCA;
  }

  // Nav: second level (shown on .active)
  .nav {
    display: none; // Hide by default, but at >768px, show it
    padding-bottom: 10px;
  }

  .nav > li > a {
    padding-top: 1px;
    padding-bottom: 1px;
    padding-left: 30px;
    font-size: 12px;
    font-weight: normal;
  }

  .nav > li > a:hover,
  .nav > li > a:focus {
    padding-left: 30px;
  }

  .nav > .active > a,
  .nav > .active:hover > a,
  .nav > .active:focus > a {
    padding-left: 29px;
    font-weight: 400;
  }
}

// Show and affix the side nav when space allows it
@media (min-width: 992px) {
  .s2-docs-sidebar .s2-docs-sidenav {
    padding-top: 40px;
    transition: border-color .2s;
    border-left: 1px solid transparent;
  }

  .s2-docs-sidebar.affix .s2-docs-sidenav {
    border-left-color: #eee;
  }

  .s2-docs-sidebar .nav > .active > ul {
    display: block;
  }

  // Widen the fixed sidebar
  .s2-docs-sidebar.affix,
  .s2-docs-sidebar.affix-bottom {
    width: 213px;
  }

  // Undo the static from mobile first approach
  .s2-docs-sidebar.affix {
    position: fixed;
    top: 0px;
  }

  // Undo the static from mobile first approach
  .s2-docs-sidebar.affix-bottom {
    position: absolute;
  }

  .s2-docs-sidebar.affix-bottom .s2-docs-sidenav,
  .s2-docs-sidebar.affix .s2-docs-sidenav {
    margin-top: 0;
    margin-bottom: 0;
  }
}

@media (min-width: 1200px) {
  // Widen the fixed sidebar again
  .s2-docs-sidebar.affix-bottom,
  .s2-docs-sidebar.affix {
    width: 263px;
  }
}

/* Back to top (hidden on mobile) */
.back-to-top {
  display: none;
  padding: 4px 10px;
  margin-top: 10px;
  margin-left: 10px;
  font-size: 12px;
  font-weight: 400;
  color: #999;

  &:hover {
    color: #428BCA;
    text-decoration: none;
  }

  @media (min-width: 768px) {
    display: block;
  }
}