Originally Posted by Stodder
@Pablo: What if the reference is to a common internal font like one of the big six? And do you embed fonts for body text or just headers?
Even if you try to make references to internal fonts common to several readers, I don't think they will be located in the same path in all of them, so you will need some sort of "conditional CSS" (don't know if such a thing exists in the specification). People also look at their books in ADE, calibre viewer, ePubReader, etc., even if they don't read them in their PC.
I think that in the near future most readers will allow some selection of built-in fonts when no font is specified in the css or even partial or total css override, so font-embedding may become less important.
I usually specify the same font for body and headers.