Ugh. It's most likely produced by CSS flattening tools--I've seen many big-name publisher stylesheets sporting "font-size: normal;" stanzas. And since some seem to run a preprocessor on the source markup before feeding it to kindlegen, it infects the output as well. kindlegen does warn about this, but allows it through regardless, and people ignore warnings when they seem to cause no ill effects at first. Arguably a kindlegen bug, but, well...
Incidentally, you might want to prepare yourself for "vertical-align: sup" instead of "super" as well
