title: how to add space between column BOOTSTRAP 4
body: <p>How can I add space between these two columns.</p>
  
  <pre><code>&lt;div class="row "&gt;
      &lt;div class="col-md-6 shadow"&gt;
              ...
      &lt;/div&gt;
      &lt;div class="col-md-6  shadow "&gt;
              ...
      &lt;/div&gt;
  &lt;/div&gt;
  
  </code></pre>