<html xmlns="http://www.w3.org/1999/xhtml" xmlns:m="http://www.w3.org/1998/Math/MathML">
<head>
<style type="text/css">
[class="wide"] { width: 100000000px }
</style>
<script type="text/javascript">
function boom()
{
document.getElementById("targ").appendChild(document.getElementById("cm").cloneNode(true));
}
</script>
</head>
<body onload="boom();">
<table>
<tbody>
<td><m:mrow class="wide" id="cm"></m:mrow></td>
<tr><m:mrow id="targ"></m:mrow></tr>
</tbody>
</table>
</body>
</html>