title: Change CSS with javascript using getElementById
body: <p>I do not know how to access a specific CSS using javascript.</p>
  
  <p>Let us say,</p>
  
  <pre><code>#menu { color: red; }
  </code></pre>
  
  <p>can be accessed by</p>
  
  <pre><code>document.getElementById('menu').style.color = "blue";
  </code></pre>
  
  <p>But I want to access</p>
  
  <pre><code>#menu li a { height: 10%; }
  </code></pre>
  
  <p>How do I access that using document.getElementById() ?</p>