title: How to fill the the available height on screen with the div for any height?
body: <p>I want to fill the screen (width and height) on any size with a <code>&lt;header&gt;</code>:</p>
  
  <pre><code>&lt;header&gt;&lt;/header&gt;
      &lt;div id="content"&gt;&lt;/div&gt;
  &lt;footer&gt;&lt;/footer&gt;
  </code></pre>
  
  <p>The <code>&lt;header&gt;</code> should always fill the whole screen on any height of monitor also in iPad, such that the content of <code>&lt;div id="content"&gt;</code> will only be seen after scrolling, not before that.</p>