<!DOCTYPE HTML> <html style="overflow:hidden" class="reftest-wait" reftest-displayport-w="800" reftest-displayport-h="2000"> <body> <div id="x" style="position:absolute; width:400px; height:400px; background:red;"> You should not see any red </div> <script> function doTest() { document.getElementById('x').style.visibility = 'hidden'; document.documentElement.removeAttribute("class"); } window.addEventListener("MozReftestInvalidate", doTest, false); </script> </body> </html>