title: DOCTYPE CSS problem
body: <p>When I added </p>
  
  <pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
  </code></pre>
  
  <p>line to the top of my html file, my css rules disappear in firefox. Also i can't see them with firebug. </p>
  
  <p>Do you have any idea about this problem ?</p>