<!DOCTYPE HTML> <title>Testcase, bug 1299736</title> <div id="A" style="transform: translateX(50px)"> <div id="B"> <div id="C" style="position: fixed"> </div> </div> </div> <script> document.getElementById("C").offsetLeft; // flush document.getElementById("B").style.transform = "translateX(50px)"; document.getElementById("A").style.transform = ""; </script>