title: Preload CSS file not supported on Firefox and Safari Mac
body: <p>I added the attribute rel="preload" to all css links like this : </p>
  
  <pre><code>   &lt;link rel='preload' onload='this.rel="stylesheet"' as='style' 
  id='reworldmedia-style-css'  href='style.css' type='text/css' media='all' 
  /&gt;
  </code></pre>
  
  <p>It works fine in Chrome but not in Safari or Firefox </p>