title: Bootstrap 4 beta - how to display div for sm only?
body: <p>In Bootstrap alpha 6 I could write this, to have a div's contents only show for sm:</p>
  
  <pre><code>&lt;div class="hidden-md-up hidden-xs-down"&gt;
     This would only show for sm in Bootstrap 4 alpha 6.
  &lt;/div&gt;
  </code></pre>
  
  <p>This no longer works in the Bootstrap 4 beta.</p>
  
  <p>How can I show a div's content for sm only, using bootstrap 4 beta?</p>