Bootstrap 4.0.0-alpha.6 btn-toolbar

HTML

<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css">
<div class="alert alert-danger mt-5" role="alert">
  <p class="lead mt-3">Be sure to resize the view area (make it really wide, and really narrow)! Btn-toolbar doesn't wrap on mobile view</p>
</div>
<div class="btn-toolbar" role="toolbar" aria-label="Toolbar with button groups">
  <div class="btn-group mr-2" role="group" aria-label="First group">
    <button type="button" class="btn btn-secondary">1</button>
    <button type="button" class="btn btn-secondary">2</button>
    <button type="button" class="btn btn-secondary">3</button>
    <button type="button" class="btn btn-secondary">4</button>
  </div>
  <div class="btn-group mr-2" role="group" aria-label="Second group">
    <button type="button" class="btn btn-secondary">5</button>
    <button type="button" class="btn btn-secondary">6</button>
    <button type="button" class="btn btn-secondary">7</button>
  </div>
  <div class="btn-group" role="group" aria-label="Third group">
    <button type="button" class="btn btn-secondary">8</button>
  </div>
</div>