<!DOCTYPE HTML> <html reftest-zoom="1.5" class="reftest-wait"> <body style="margin:0;"> <div id="d" style="position:absolute; top:15px; left:15px; width:100px; height:100px;"></div> <script> function doTest() { document.getElementById("d").style.background = "yellow"; document.documentElement.removeAttribute('class'); } document.addEventListener("MozReftestInvalidate", doTest); </script> </body> </html>