<html xmlns="http://www.w3.org/1999/xhtml" xmlns:m="http://www.w3.org/1998/Math/MathML">
<head>

<style type="text/css">
#q { width: 16px; height: 16px; }
#a, #b { counter-increment: chicken; }
</style>

<style id="s" type="text/css">
#a { content: 'x'; }
</style>

<script type="text/javascript">

function boom()
{
  remove(document.getElementById("s"));
  remove(document.getElementById("b"));
}

function remove(n)
{
  n.parentNode.removeChild(n);
}

</script>

</head>

<body onload="boom();">

<m:mrow id="a"/><m:mo id="q"><m:malignmark><m:msubsup/><m:munderover/><m:munder id="b"/></m:malignmark></m:mo>

</body>

</html>
