Ages ago (2010-2011 I think?), I worked on a tool that exported and packaged text into .epub format. At the time one of the biggest headaches was the lack of good font rendering in ePub readers. Apple's Books app did an okay job, but some of the others just ignored the font settings, _even when an embedded font was packaged in the file_. All the more frustrating when you consider that the text was not English, and the embedded fonts were necessary for properly rendering the code points and not displaying question marks or boxes.<p>No idea if the available readers have improved, but I'm all for this proposal of a self-contained reader.