<html xmlns="http://www.w3.org/1999/xhtml"> <head> <script type="text/javascript"> function boom() { var newTD = document.createElementNS("http://www.w3.org/1999/xhtml", "td"); newTD.setAttribute("rowspan", 3); document.getElementById("tr1").appendChild(newTD); document.documentElement.offsetHeight; var newTR = document.createElementNS("http://www.w3.org/1999/xhtml", "tr"); document.getElementById("table").appendChild(newTR); } </script> </head> <body onload="boom();"> <table id="table">AAAA<tr id="tr1"></tr><tr><td><div style="-moz-column-width: 1px;">B C</div></td></tr></table> </body> </html>