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

<head>
<style>
[class="capleft"] { caption-side: left; }
[class="collapse"] { visibility: collapse; }
</style>
</head>

<body>

<div>
  <math xmlns="http://www.w3.org/1998/Math/MathML" display="block" class="collapse">
    <mtable>
      <mtr>
        <mtd><mi>x</mi></mtd>
        <mtd><mi>y</mi></mtd>
      </mtr>
      <html:caption class="capleft">
        <mtd><mi>z</mi></mtd>
        <mtd><mi>w</mi></mtd>
      </htm