mathml on iOS -- mtable row spacing

Question

This is driving me crazy. I need spacing between the rows of my mtable elements. For now, I am content to get it in the html; once I have that working, I'll try to move it to CSS.

Here are some things I am trying. In each case, I've set the amount of space crazy large so that if it works it will be unmistakable. But so far I can't see any space.

The implementation of mathML is incomplete. But until now, I've been able to find work-arounds for almost everything.

    <math>
        <mtable rowspacing="10ex">
            <mtr padding="40px">
                <mtd padding="40px">
               <!-- remainder of the table here -->

another attempt, equally useless:

    <math>
        <mtable framespacing="40px 40px">
            <mtr margin="40px">
                <mtd margin="40px">
               <!-- remainder of the table here -->

Answer 1

This did it:

  <mtd style="padding:10px 0 10px 0">