mphantom_colors

mphantom with mathbackground.

W3C sample	WIRIS
	$$a+\phantom{a}+a+\phantom{a}$$

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mi>a</mi>
    <mo>+</mo>
    <mphantom>
      <mi>a</mi>
    </mphantom>
    <mo>+</mo>
    <mi mathbackground="#80FF80">a</mi>
    <mo>+</mo>
    <mphantom mathbackground="#80FF80">
      <mi>a</mi>
    </mphantom>
  </mrow>
</math>

Author: Bruce Miller