<!DOCTYPE html>
<html class="reftest-wait">
<head>
<meta charset="UTF-8">

<style>
#modified {
  left: 0px;
}
</style>

<script type="text/javascript">
function doTest() {
  document.getElementById("modified").style.left = "10px";
  document.documentElement.removeAttribute("class");
}

window.addEventListener("MozReftestInvalidate", doTest);
</script>

</head>
<body>
<div style="opacity:0.9">
  <div style="position:fixed; left:300px; top:300px; width:200px; height:200px; background-color:red; z-index:-10"></div>
  <div style="width:200px; height:200px; position:relative; background-color:green" id="modified">
    <div style="opacity:0.9">
      <div style="position:fixed; left:300px; top:300px; width:200px; height:200px; background-color:green; z-index:-10"></div>
    </div>
  </div>
</div>
</body>
</html>