On: The fastest math typesetting library for the web

[throwaway290]

I guess <mover> is semantic enough, actually? Though I don't get why the engine doesn't just know to render the arrow appropriately and it needs all those <mo stretchy> things with inline styling.

[runarberg → throwaway290]

<mover> has a boolean accent attribute so I guess you can write:

    <mover accent="true">
      <mi>B</mi>
      <mo>→</mo>
    </mover>

[throwaway290 → runarberg]

So maybe that's a problem with a particular latex->mathml convertor, but the idea itself should work.