Formatting of right hand side of equation should be identical to formatting of left hand side
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
<mfrac>
<mn>1</mn>
<mn>42</mn>
</mfrac>
<mo>=</mo>
<mfrac linethickness="1">
<mn>1</mn>
<mn>42</mn>
</mfrac>
</math>
Author: George Chavchanidze, Opera Software ASA