title: Adding namespace to a css should make the IDE validate the code?
body: <p>In a CSS file, using Eclipse IDE, adding the header:</p>
  
  <pre><code>@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
  </code></pre>
  
  <p>should make eclipse check the elements for errors? (becouse it's not doing it).</p>
  
  <p>If not, what's the difference of adding that header or not?</p>