title: HTML5 + CSS and setting the width of <HEADER>
body: <p>I got the following css:</p>
  
  <pre><code>div#header, header { 
      height: 88px; 
      width: 100%; 
      background-image: url('/images/header.jpg'); 
      background-repeat:no-repeat; 
  }
  </code></pre>
  
  <p>And the following HTML:</p>
  
  <pre><code>&lt;header&gt;&lt;/header&gt;
  &lt;div id="header"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>The second HTML-line does exactly what I want it to do. However, the first html-line (&lt; header >) does not.</p>
  
  <p>I'm using Firefox 3.6.8. In firebug the markup for both html-line looks exactly the same. 
  In Internet explorer I have the same problem. Only Chrome displays the code as expected.</p>
  
  <p>I'm pretty confused right now. How to fix this?</p>