mphantomScolor4

W3C sample	WIRIS
	$A\phantom{A}A$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <mi>A</mi>
    <mstyle color="Red" mathbackground="Green">
      <mphantom>
        <mi>A</mi>
      </mphantom>
    </mstyle>
    <mi>A</mi>
  </mrow>
</math>

Author: Robert Miner and Jeff Schaefer, Geometry Technologies