title: fit wrapper to 100% width and height
body: <p>I would like to create a <code>div</code> which fits the full height and width of the browser viewport. I just thought about simple css like:</p>
  
  <pre><code>#wrapper { width: 100%;
             height: 100%;
             background-color: red;
  }
  </code></pre>
  
  <p>but it  does not work for the height. The <code>#wrapper</code> does not have any height. Why?</p>
  
  <p>Thanks in advance.</p>