<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>fractions linethickness</title>
  </head>
  <body>
    <p>This test passes if you see a fraction without fraction bar.</p>
    <math>
      <mfrac>
        <mspace width="20px" height="5px" style="background: blue"></mspace>
        <mspace width="20px" height="5px" style="background: cyan"></mspace>
      </mfrac>
    </math>
  </body>
</html>