I haven’t tested these thoroughly (maybe the readers will change between serif & sans serif) but it seems that each bit of software uses its own font and ignores what the epub has set them to.
If you go through the CSS you’ll find all of the font family information is stripped out. 90% of the time the book reader won’t have the font you used to write with or put into your compile settings, anyway. It is considered best practices to strip font declarations out, and particularly for body text, which should be left up to the reader theme/preference.
As for embedding, you can read up on our reasoning for why that isn’t done fully automatically. As I hinted at toward the end, it’s very easy to set things up for them though, since you can add your own CSS. There are a 1,001 guides out there for creating the CSS you need to declare a font and then use it, so once you have that put together, just paste the results into the CSS compile format pane. In the future, all you’ll need to do with Sigil is add the font files with File ▸ Add ▸ Existing Files...
. It’ll do all of the difficult work for you (declaring them in the manifest and so forth), and if you have the CSS set up right for where it puts the fonts, that should be the only command you need to use. Save it and you’re done.
And while I’m about it, maybe tidy up the HTML / CSS to keep the download to a minimum and less chances of ebook readers mis-interpreting what I’m trying to achieve.
It’s a completely different approach, and a separate learning curve from Scrivener’s built-in ebook generator, but for anyone who cares about that aspect of the ebook, I like to recommend at least giving Scrivener’s Pandoc integration to try. It’s easy to install, and after a restart of Scrivener you’ll find new compile options at the bottom of the “Compile For” dropdown. Unless you also want to write with Markdown, you’ll want to enable the Convert rich text to Markdown option in the general options tab of compile overview.
The main point of difference with “normal” Scrivener usage is that you won’t be using Scrivener to establish the formatting, that will be 100% the CSS (which you can control from the “Pandoc Settings” compile format pane); feel free to pilfer any CSS from our stock settings with copy and paste. That does also mean a heavier use of styles to establish formatting. It might take a little more up-front work to learn a new approach and establish a look you like, but it will be time well invested for the future. You can just build off of what you already know and have done. The question, to my mind, is whether that investment of time is better spent than trawling through a “clean up” checklist every time you compile.
The result though is super clean. It shouldn’t take but a few minutes to try it out, and if it’s not to your liking you can switch right back to what you were doing before. All of the settings for this workflow are self-contained and “vanish” when switching “Compile For” back to ePub3.