<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>none should render as an mrow (reference)</title>
  </head>
  <body>
    <math>
      <mrow>
        <mspace width="10px" height="20px" style="background: cyan;"></mspace>
        <mspace width="30px" height="10px" depth="5px" style="background: blue;"></mspace>
        <mspace width="20px" height="15px" depth="30px" style="background: lightblue;"></mspace>
        <mspace width="25px" depth="20px" style="background: cyan;"></mspace>
        <mspace width="40px" height="5px" depth="15px" style="background: blue;"></mspace>
        <mspace width="20px" height="35px" depth="5px" style="background: lightblue;"></mspace>
      </mrow>
    </math>
  </body>
</html>
