<html> <head> <script> function runTest() { document.body.offsetLeft; document.getElementById('target').style.paddingLeft = '400px'; document.body.offsetLeft; document.getElementById('positioned').style.left = ''; document.getElementById('positioned').style.width = '200px'; } </script> </head> <body onload="runTest()"> <div style="position:absolute;left:400px;top:0px;width:100px;height:100px;background-color:red"></div> <div style="position:absolute;left:0;top:0"> <div style="padding-left:100px" id="target"><div id="positioned" style="position:absolute;top:0;left:0;width:100px;height:100px;background-color:green"></div> </div> </div>