title: Can't get combobox (select tag) to work with py-4 spacing
body: <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;link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/&gt;
  &lt;div class="form-row"&gt;
    &lt;div class="col-md-6"&gt;
      &lt;div class="form-group"&gt;
        &lt;label class="small mb-1" for="selectType"&gt;Register as&lt;/label&gt;
          &lt;select class="form-control py-4" id="selectType"&gt;
            &lt;option value="1"&gt;Student&lt;/option&gt;
            &lt;option value="2"&gt;Mentor&lt;/option&gt;
        &lt;/select&gt;
      &lt;/div&gt;
    &lt;/div&gt;
   &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>I get <a href="https://i.stack.imgur.com/wzJIg.png" rel="nofollow noreferrer">this </a>as a result.</p>
  <p>It only works when i reduce it to py-2 but the rest of the form works perfectly with py-4.
  Any suggestions?</p>