No syntax highlighting, only in Firefox, and only on newer built crates

[rossmacarthur]

I can't figure out why this is happening.

• Only happens on https://docs.rs not https://doc.rust-lang.org/std/
• Happens on multiple crates but not all. It appears to only happen on crates built after a certain date (all older crates seem to be fine).
• I am using Firefox 67.0 (64-bit) on macOS Mojave.
• I have factory reset my Firefox, so deleted all addons, cookies, history, cache, everything and it still happens.
• If I download the crate and run cargo doc or cargo +nightly doc I have no problems.
• Not related to internet connection, happens on all networks.
• No errors in console or anything.

Examples

https://docs.rs/url/1.7.2/url/

https://docs.rs/url/1.7.1/url/

[GuillaumeGomez]

The strange thing is that the rules are present but don't seem to be applied. I have no idea what's going on...

[rossmacarthur]

This appears to be related to the "Source Code Pro" font. If I disable it, then the syntax highlighting works. I'm not sure if this is Firefox or a mismatch between font files and supported font-weights.

If I change the CSS from

@font-face {
 font-family:'Source Code Pro';
 font-style:normal;
 font-weight:400;
 src:url("SourceCodePro-Regular.woff") format('woff');
}

and use my local version

@font-face {
 font-family:'Source Code Pro';
 font-style:normal;
 font-weight:400;
 src:local("Source Code Pro");
}

It works perfectly

[GuillaumeGomez]

cc @nical

[Manishearth]

We ... uh, fixed this when we updated Source Code Pro. I'm not sure why it's broken again.

[Manishearth]

Wait, we fixed this in rustdoc. docs.rs may not have updated its fonts

[rossmacarthur]

I no longer have this issue.