Trigger dropdown menus above elements by adding .dropup to the parent.

<div class="btn-group dropup">
  <button type="button" class="btn btn-default">Dropup</button>
  <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    <span class="caret"></span>
    <span class="sr-only">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu">
    <!-- Dropdown menu links -->
  </ul>
</div>

Related classes: