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Bootstrap class: .nav-pills with dropdown

<ul class="nav nav-pills">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">Dropdown</a>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
    </div>
  </li>
</ul>

Preview