title: How to add a vertical line between two columns in Bootstrap 4
body: <p>I have two <code>div</code> columns. I want to display a line between them on the screen.</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div class="container-fluid"&gt;
    &lt;div class="row"&gt;
      &lt;div class="col-md-3"&gt;&lt;/div&gt;
      &lt;div class="col-md-9"&gt;&lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>