[Havner]

Originally Posted by jackie_w

I believe the Kobo built-in fonts are obfuscated so overwriting the .ttf files with your own versions is probably not an option.

Yeah, I just found a note on these forums that they are encrypted. Still, it doesn't mean there is no way to replace them, just that we cannot modify them.

I'm not sure how helpful the following will be for you, but I'll outline how I solved this problem for kepubs on my own devices.

Like I said I know how to do this by modifying CSS files of the book. I'm looking for more of a "system" solution. Thanks anyway.

With kepubs there's no need to add extra @font-face statements.

This is new to me though. I was able to point epubs to sideloaded fonts (with res:///fonts/), but for kepubs the only way I found was to actually embed the font in the book itself. Both cases required @font-face. I'll have a try. Thanks.

I also know how to do this automatically with Calibre and kobo_extra.css.

EDIT: reread your post, you're not modifying the default sans and sans-serif definitions, you're replacing their usage directly with a font name. Ok, that's why the @font-face is not required. To change the definitions to new fonts it is still required. Still, I get the final effect is the same for how the book looks.