<!DOCTYPE html>
<html>
  <head>
    <title>mfrac bevelled</title>
  </head>
  <body>
    <math>
      <mfrac style="font-size: 300%">
        <mspace width="20px" height="20px" mathbackground="red"></mspace>
        <mspace width="20px" height="20px" mathbackground="red"></mspace>
      </mfrac>
    </math>
  </body>
</html>
