<!DOCTYPE html>
<html class="reftest-wait">
  <head>
    <link rel="stylesheet" type="text/css" href="style.css">
  </head>
  <body>
    <div id="container" style="border-width: 10px; padding: 50px"
      >surrounding <span id="rel"
        style="left: 0; top: 0;"
        >position&#10;relative</span> text</div>
    <script>
      document.addEventListener("MozReftestInvalidate", function() {
        var rel = document.getElementById("rel");
        rel.style.top = "50%";
        rel.style.left = "50%";
        document.documentElement.removeAttribute("class");
      }, false);
    </script>
  </body>
</html>