<!DOCTYPE html> <html> <head> <title>Test mpadded</title> </head> <body> <math> <!--height in term of height should not depend on the characters--> <mpadded mathbackground="red" height="100height" depth="0"> <mphantom> <mtext style="font-family: monospace">_</mtext> </mphantom> </mpadded> </math> <math> <mpadded mathbackground="red" height="100height" depth="0"> <mphantom> <mtext mathvariant="monospace">i</mtext> </mphantom> </mpadded> </math> </body> </html>