title: how to use Div relative height 100%?
body: <p>I am a beginner in website design. I would like to have a dynamic height of content. So I do something like this:</p>
  
  <pre><code>&lt;div style="position:relative;width:100%;height:100%;" id="content"&gt;
      ....
  &lt;/div&gt;
  
  &lt;div style="position:relative;width:2000px;height:498px;"&gt;
      &lt;?php include('footer.php'); ?&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>However the div of footer does not detect the height of content. What should I do? Thanks.</p>