At some point, the updated ePub books does not contain the italic / bold fonts anymore. This is a problem in Sony Reader PRS-700 because it does not seem to italicize / bolden the embedded font but just uses the horrible built-in font. Hence the result is awkward looking emphasized text in the middle of a paragraph.
IIUC, the missing fonts are:
However, including all these fonts will increase the size of the book by 2~4 MB, so it might be a better idea to exclude some unused ones. For instance, I can't find bold or bold italic text in my books easily so only italic versions could be included if I understood correctly.
More advanced solution would be to analyze all the characters used in the ePub text and remove unreferenced glyphs from the font files to reduce its size significantly.
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