title: hidden-sm-down on Bootstrap4 not working
body: <p>I'm trying to make my images be above my text on m+ devices, and below the text on sm- devices. I'm using Bootstrap4, and to my knowledge following all the tutorials given from Bootstrap - yet it's not hiding my images.   Thanks for the help in advance.</p>
  
  <p>Here is my code: </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="container"&gt;
  &lt;div class="row"&gt;
  &lt;div class="hidden-sm-down"&gt;
  &lt;div class="col-md-6"&gt;
  &lt;img class="img-fluid" src="img/finding.svg" onerror="this.src='img/finding.png';this.onerror=null;" alt=""&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="col-md-6 col-sm-12"&gt;
  &lt;h5 class="heading"&gt;Get SMS notifications for new dates&lt;/h5&gt;
  &lt;p class="sell"&gt;
  This is where the text would go.
  &lt;/p&gt;
  &lt;/div&gt;
  &lt;div class="hidden-md-up"&gt;
  &lt;div class="col-md-6"&gt;
  &lt;img class="img-fluid" src="img/finding.svg" onerror="this.src='img/finding.png';this.onerror=null;" alt=""&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>