<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <style type="text/css">
      html { background-color: white }
      mi { color: white; }
      mo { color: red; }
    </style>
  </head>
<body>
  <math xmlns="http://www.w3.org/1998/Math/MathML">
    <mover>
      <mi>a</mi>
      <mo>&#x302;</mo>
    </mover>
  </math>
</body>
</html>
