 are not mapped to CSS have no effect.
    -->
  <p class="TestContainer" id="mspace">
    <math>
      <mstyle width="50px" height="50px" depth="50px">
        <mspace style="background: lightblue"></mspace>
      </mstyle>
    </math>
    <math>
      <mstyle>
        <mspace style="background: lightblue"></mspace>
      </mstyle>
    </math>
  </p>
  <p class="TestContainer" id="mfrac">
    <math>
      <mstyle linethickness="50px">
        <mfrac>
          <mn>1</mn>
          <mn>2</mn>
        </mfra