various accent problems

This example looks bad with TeX fonts

    <mover>
      <mi>H</mi>
      <mo>&#x02DD;</mo>
    </mover>

This example looks bad with STIX on HTML-CSS (no accent -- SVG is fine),

    <mover>
      <mi>H</mi>
      <mo>&#x0302;</mo>
    </mover>