[HTML-CSS] With mathsize > 30pt, accents begin to disappear

In the example

<math mathsize="30pt">
    <mover>
      <mrow>
        <mi>X</mi>
        <mi>X</mi>
      </mrow>
      <mo>&#x005E;<!-- ^ --></mo>
    </mover>
</math>

the accent is begin clipped, and for larger sizes, the clipping is greater (until 36pt when it disappears entirely).