tangor - 12:32 pm on Dec 22, 2011 (gmt 0)

You've indicated a percent, then use an em against a basefont?

Use one or the other. I K.I.S.S. with font sizing. (ie, either em OR percent OR pixel... I never mix them)

editing myself: I specify a font
Later I specify a font size regarding its use such as:

Heading
BodyText (p)
etc.

I don't start at 100% then base at 62.5% and expect 1.2em to be 12 points. Asking a lot of calculation from the browser. Browser only has to deal with one kind of math and results will be more predictable.