Every attempt (even my own) to fix EPUB or replace PDFs with something like EPUB to date either underestimates the problem or misunderstands it entirely.
First EPUB only supported fixed versions of XHTML and CSS. Stability and portability, right? But then development gets harder and harder the more HTML5 evolves and diverges from the original snapshot.
Update to a living spec? But then you lose that stability and predictability.
