<html xmlns="http://www.w3.org/1999/xhtml"> <head> <script> function boom() { document.getElementById("x").appendChild(document.createElementNS("http://www.w3.org/1999/xhtml", "span")); } </script> </head> <body onload="boom();"> <div style="-moz-column-count: 15;"><div style="-moz-column-count: 15;" id="x"><td style="display: block; height: 2.5em;"></td></div></div> </body> </html>