The Tor Browser / file revision

 <treerow xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="zebra">

 <script xmlns="http://www.w3.org/1999/xhtml"><![CDATA[

 function doe(){

   document.getElementById('b').parentNode.removeChild(document.getElementById('b'));

   document.getElementById('c').parentNode.removeChild(document.getElementById('c'));

 }

 setTimeout(doe, 200);

 ]]></script>

 <box id="a"/>

 <mtr xmlns="http://www.w3.org/1998/Math/MathML">

 <box xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="zebra" id="c"/>

 </mtr>

 <box style="display: inline;" id="b"/>

 <style xmlns="http://www.w3.org/1999/xhtml">

 #a { counter-reset: chicken 11 egg; }

 #b { counter-increment: chicken -1 egg; }

 *[class=zebra] { counter-increment: chicken 5; }

 </style>

 </treerow>