When a ePub does not have embedded font, InkBook reader will use DroidSansFallback.ttf to be the publisher's font.
If you want to change fonts of InkBook reader, you could replace /system/fonts/DroidSansFallback.ttf with your favorite font.
Only the font could be replaced, other 5 can't.
Of course, to replace DroidSansFallback.ttf, it must be root prime at first.
And remember to backup.
