I am testing an epub file which I rolled up on my own. (I.e., I didn't use InDesign).
I deliberately did not specify a font for my ebook because the major ebook readers include their own fonts (or use system fonts). (Also, btw, it is very difficult to keep up with what readers use what fonts).
As it happens, I did include an embedded font for a special bit of content (it was a handwritten font), but that was only one part of the epub file.
I have tested the epub file on ibooks and Google Play. Everything renders perfectly. I can choose from about 8-10 different fonts on every epub reading software I have.
I tested the epub file on Adobe DE app on Android. Everything looks good, except that there are no ways to choose font! ADE doesn't give you any information about what fonts are being used here (although you can change size).
What's going on here? Does DE want to force publishers to use embedded fonts? Does DE secretly have a few dozen fonts inside the mobile app? Or is DE deliberately stripped down to allow ebook distributors to provide their own fonts on their reading apps?
Are there any DE fonts which are on every platform? i.e. , common fonts like Georgia, Helvetica, Verdana, etc
I would hate to be forced to dump an .otf font into my ebook file just because the reader just doesn't support any natively. Do you have any recommendations?
UPDATE: Can I assume that ADE just applies serif and sans-serif to all content inside an epub file? Does DE have an algorithm for determining which html elements to apply a sans-serif font to?