twbs--bootstrap/docs/assets/scss/_sidebar.scss

//
// Side navigation
//

.bd-sidebar {
  @include media-breakpoint-up(md) {
    padding-left: 1rem;
  }
}

.bd-search {
  position: relative;
  margin-bottom: 1.5rem;

  .form-control {
    height: 2.45rem;
    padding-top: .4rem;
    padding-bottom: .4rem;
    background-color: #fafafa;

    &:focus {
      background-color: #fff;
    }
  }
}

.bd-search-results {
  right: 0;
  display: block;
  padding: 0;
  overflow: hidden;
  font-size: .9rem;

  &:empty {
    display: none;
  }

  .dropdown-item {
    padding-left: .75rem;
    padding-right: .75rem;

    &:first-child { margin-top: .25rem; }
    &:last-child { margin-bottom: .25rem; }
  }

  .no-results {
    padding: .75rem 1rem;
    color: #7a7a7a;
    text-align: center;
    white-space: normal; // Undo .dropdown-item defaults
  }
}


.bd-sidenav {
  display: none;
}

.bd-toc-link {
  display: block;
  padding: .25rem .75rem;
  color: $gray;
}
.bd-toc-link:hover,
.bd-toc-link:focus {
  color: $brand-primary;
  text-decoration: none;
}
.active > .bd-toc-link {
  font-weight: 500;
  color: $gray-dark;
}
.active > .bd-sidenav {
  display: block;
}

.bd-toc-item.active {
  margin-top: 1rem;
  margin-bottom: 1rem;
}
.bd-toc-item:first-child {
  margin-top: 0;
}
.bd-toc-item:last-child {
  margin-bottom: 2rem;
}

// All levels of nav
.bd-sidebar .nav > li > a {
  display: block;
  padding: .25rem .75rem;
  font-size: 90%;
  color: #99979c;
}
.bd-sidebar .nav > li > a:hover,
.bd-sidebar .nav > li > a:focus {
  color: $brand-primary;
  text-decoration: none;
  background-color: transparent;
}
.bd-sidebar .nav > .active > a,
.bd-sidebar .nav > .active:hover > a,
.bd-sidebar .nav > .active:focus > a {
  font-weight: 500;
  color: $gray-dark;
  background-color: transparent;
}