select2/docs/_sass/_nav.scss

.s2-docs-nav {
  margin-bottom: 0;
  border-color: #eee;
  background-color: #f6f6f6;

  .navbar-brand {
    font-weight: 500;
    img {
      margin-right: 4px;
    }
  }

  .navbar-nav > .active > a,
  .navbar-nav > .active > a:hover,
  .navbar-nav > .active > a:focus {
    background-color: #f0f0f0;
    color: #000;
  }

  @media (min-width: 768px) {

    .navbar-nav > li > .dropdown-menu:before {
      position: absolute;
      top: -21px;
      left: 24px;
      display: block;
      width: 0;
      height: 0;
      border-color: rgba(0, 0, 0, 0) rgba(0, 0, 0, 0) rgba(0, 0, 0, 0.1);
      border-style: solid;
      border-width: 10px;
      content: "";
    }

    .navbar-nav > li > .dropdown-menu:after {
      position: absolute;
      top: -20px;
      left: 24px;
      display: block;
      width: 0;
      height: 0;
      border-color: rgba(0, 0, 0, 0) rgba(0, 0, 0, 0) #FFF;
      border-style: solid;
      border-width: 10px;
      content: '';
    }

    .navbar-nav .dropdown-menu {
      border-radius: 4px;
      border-color: #ddd;
      margin-top: -1px;
    }
  }
}