title: Flicker/slow css when loading contentn and css async
body: <p>so I am loading a new page and a css file for this page via ajax. </p>
  
  <p>After all the css files are added to the page, I set the opacity of the page to 1, but it shows up without the css applied and after a second or so the css is applied. This looks horrible, how can I avoid it?</p>
  
  <p>I did not find a clean way to detect when css fully loaded. </p>
  
  <p>Any idea why it shows up like this? I think the css might not be fully downloaded yet, but as I said, I do not know how to avoid that. </p>