title: How to mirror iframe without loading the same URL twice? CSS doesn't activate
body: <p>I have two iframes side by side and want only 1st one to be loading URL. After 1st one finishes loading, I want 2nd iframe to have the same content, without loading the same URL. Here is what I tried:</p>
  
  <p>Testing here: <a href="https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_script" rel="nofollow noreferrer">https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_script</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;!DOCTYPE html&gt;
  &lt;html&gt;
  
  &lt;head&gt;
    &lt;script&gt;
      $(document).ready(function() {
        $('#iframeID1').on('load', function() {
          $('#iframeID2').contents().find('html').html($('#iframeID1').contents().find('html').html());
        });
      });
    &lt;/script&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
    &lt;iframe id="iframeID1" src="https://www.w3schools.com/" frameborder="0" scrolling="no" width="180px" height="512" align="left"&gt;
      &lt;/iframe&gt;
  
    &lt;iframe id="iframeID2" frameborder="0" scrolling="no" width="180px" height="512" align="middle"&gt;
      &lt;/iframe&gt;
  &lt;/body&gt;
  
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>However, this is what 2nd iframe (on the right) shows (fails to load CSS?):</p>
  
  <p><a href="https://i.stack.imgur.com/WMgI1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WMgI1.png" alt=""></a></p>