<html> This test scrolls the iframe body by fractional scroll offset but the fixed position element should stay fixed
<body style='height:2000px'>
  <iframe srcdoc="
    <body style='width:1000px;height:2000px;background-color:green'>
    <div style='position:fixed; background-color:red; width: 100px; height: 100px; top: 0px; left: 0px;'> </div>
    <input type='checkbox' style='margin-top:100px'> the checkbox should not be blurred
    </body>
    <script>
      window.scrollTo(0, 0.5)
    </script>
  "</iframe>
</body>
</html>