Thanks for picking this up!

Just a few small things, and I think I'd be happy merging this:

• I think Source Code Pro needs a copy of the OFL license (at least the terms seem to indicate it needs to be included when bundled).
• I'd be happy to drop the woff fonts. AFAIK, the older browsers which just use default fonts instead, right?
• I think there should be a mechanism to skip copying the fonts to the output directory if you are not using them. I think I personally would prefer, if fonts.css is overridden, to skip copying the fonts. I think that would be nice, as it would avoid extra configuration needed, and if you are overriding fonts.css, you're probably specifying your own fonts anyways. I'm not sure how difficult that will be to detect, though.
• The documentation needs to be updated. I think theme/README.md would be a good place to indicate that fonts can be overridden, and what the implications are.

Hey!

First of all, I didn't want the .woff files to end up in the git history (as they sum more than 500 kB) and the commits were very confusing, so I just force pushed a single simpler commit with the authors of both #848 and #1189 as co-authors.

Addressing your points:

• OFL license added 👍
• Yes, older browsers will fallback to system fonts, up to the last font specified in general.css). In the case of Open Sans any sans-serif font will be used and in the case of Source Code Pro any monospace font will be used (with a lot of fallbacks apparently)
• I've actually implemented skipping copying fonts when fonts.css is overridden, but found it pretty clunky. For example, creating a theme with mdbook init --theme (which generates the default theme) would stop fonts from being copied. I've kept that implementation at another branch. The implementation in this PR actually adds fonts.css to /fonts and not to the theme, preventing it and all fonts from being copied with a new option: no-copy-fonts. I'd like it better for the option to be copy-fonts but then I'd have we'd have to provide impl Default for HtmlConfig instead of deriving and I'm not sure about your opinion on this.
• Docs for the configuration file updated.

What do you think?

I didn't want the .woff files to end up in the git history

How about using build.rs to download fonts at build time?

Ah, good catch! I think I would prefer to avoid the no- prefix. I think it would be fine to have a manual Default impl.

How about using build.rs to download fonts at build time?

I would prefer not to have a network dependency like that.

Ah, good catch! I think I would prefer to avoid the no- prefix. I think it would be fine to have a manual Default impl.

Great! In the next few days I'll fix this.

Done! I also forgot to copy the fonts' licenses themselves to the output directory, which is now fixed 😅 .