title: Why is the responsive function not working?
body: <p>In the given <a href="https://codepen.io/zameelm10/pen/eYgbNBZ" rel="nofollow noreferrer">link</a>, why is the reponsive effect of the navbar disappearing not working ?</p>
  <pre><code> &lt;nav&gt;
  &lt;li&gt;Hello&lt;/li&gt;
  &lt;/nav&gt;
  
  
  &lt;style&gt;@media screen and (max-width:400px) {
     .nav {
        display: none;
     }
  &lt;/style&gt;
  </code></pre>