Originally Posted by Peter Sorotokin
This is very true (although, I'd say this is CSS problem in general - it is not much easier with DTBook, for instance) and I see a lot of friction there as devices start to utilize user stylesheets more. Note that doing blind overrides (e.g. overriding justify or font on p element) is not very good solution because some parts of the book may require particular style: for instance, poetry and code samples should be left-justified and math formulas typically require a specific font. What is needed is a guide on how to author documents so that user stylesheets can selectively override only things which are meant to be overridable.
Basically, we need a way to make EPUB files more semantic and editor/converter support for outputting semantic markup.