<!DOCTYPE HTML> <html class="reftest-wait"> <head> <style> #d { transition:opacity 1s; } #p { position:absolute; } </style> </head> <body> <div id="d"> Hello <span id="s"><div id="p">Kitty</div></span> </div> <script> var d = document.getElementById("d"); d.getBoundingClientRect(); d.style.opacity = 0.3; window.addEventListener("MozReftestInvalidate", function() { setTimeout(function() { document.body.removeChild(d); document.documentElement.removeAttribute("class"); }, 50); }, false); </script> </body> </html>