Untitled

<!DOCTYPE html>
<html>

  <head>
    <style>
      html {
        background:black;
      }
      .fixed {
        position:fixed;
        height:30px;
        background:#fff;
      }
      
      #x {
        margin-top:30px;
      }
      
    </style>
  </head>

  <body>
    
    <div style="position:absolute; left:77; top:77; width:377; height:377; clip:rect(0,381,381,0); background:#FFF;">
     <div class="fixed">AAA</div>
     
     <iframe id="x" src="http://tutorialzine.com/2015/12/creating-your-first-desktop-app-with-html-js-and-electron/#comment-573515" width="600" height="800" marginwidth="0" marginheight="0" frameborder="no" scrolling="yes">
     </iframe>
    
    </div>
  </body>

</html>