title: CSS Fixed header of unknown height
body: <p>I have a header fixed to the top of the page that can wrap creating more height when the page is resized to a smaller width.</p>
  
  <p>How do I make the the page content (#wrapper) always begin at the bottom of the header with CSS only?</p>
  
  <pre><code>&lt;body&gt;
   &lt;header&gt;
    This fixed content will wrap on small devices.
   &lt;/header&gt;
   &lt;div id="wrapper"&gt;
    This content should always begin immediately below the header.
   &lt;/div&gt;
  &lt;body&gt;
  </code></pre>