title: nav-pills nav-stacked not working
body: <p>I am trying to use nav stacked to make a vertical menu with nav pills. The problem is that It does not seem to work. It keeps the "horizontal" value. I have found solutions not implementing nav stacked but I need to use it this way. </p>
  
  <p>implementing this: </p>
  
  <pre><code>&lt;meta charset="utf-8"&gt;
  &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
  &lt;link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"&gt;
  </code></pre>
  
  <p>I have tried using older versions but then the rest of my Webpage changes, and I do not want to. </p>
  
  <pre><code>&lt;ul class="nav nav-pills nav-stacked"&gt;
  &lt;li class="nav-item"&gt;
  &lt;a class="nav-link active" href="#"&gt;Section 1&lt;/a&gt;
  &lt;/li&gt;
  &lt;li class="nav-item"&gt;
  &lt;a class="nav-link" href="#"&gt;Section 2&lt;/a&gt;
  &lt;/li&gt;
  &lt;li class="nav-item"&gt;
  &lt;a class="nav-link" href="#"&gt;Section 3&lt;/a&gt;
  &lt;/li&gt;
  &lt;li class="nav-item"&gt;
  &lt;a class="nav-link" href="#"&gt;Section 4&lt;/a&gt;
  &lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>