I'm the author of the article (the reponse not the original). I didn't say em is based on "m". All I said about em is:
"(For completeness, I should mention here that the "em" and "ex" units are exceptions to the above. The lengths 1em and 1ex do vary relative to the other units, because they depend on the font in use.)"
I'll update this to say "font size" as I didn't mean to give the impression that it was dependent the choice of font.
Comments
I'm the author of the article (the reponse not the original). I didn't say em is based on "m". All I said about em is:
"(For completeness, I should mention here that the "em" and "ex" units are exceptions to the above. The lengths 1em and 1ex do vary relative to the other units, because they depend on the font in use.)"
I'll update this to say "font size" as I didn't mean to give the impression that it was dependent the choice of font.
I was nit picking to be fair. But font size certainly does clear up the ambiguity.