<!DOCTYPE html> <html> <head> <script> function boom() { document.documentElement.offsetHeight; document.getElementById("outer").lastChild.data = "Y"; document.documentElement.offsetHeight; } </script> </head> <body onload="boom();"> <div id="outer" style="-moz-column-width: 1px;"><div style="-moz-column-width: 1px;"><div style="height: 50px;"></div><div style="float: left; height: 466px;"></div><div></div></div>X</div> </body> </html>