Short version: Is there any way I can use custom fonts with KF8 files?
In full: Apologies if this isn't the right place for this question: I recently got 3.4 on my Kindle 3, and today I tried out my first KF8 file (html -> epub via sigil and epub -> AZW3 via calibre). I've been using this trick: https://www.mobileread.com/forums/showthread.php?t=99355
to use a custom font, and on 3.4 the custom font continued working in all of my old files, but in this KF8 file the default Kindle font is showing up instead. The file itself does not have any embedded font or styling commanding that a certain font be used. Is there any way I can make that font trick work with KF8 files?