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I'm not sure if it's because I have a lot of CSS custom properties (not that many in the grand scheme of things) but I'm finding in Firefox Dev Tools changing the values of custom properties doesn't seem to do anything any more. Anyone else?

Ohhh can you give me a URL and some steps to reproduce what you're seeing?

Hiya! I've just had another look and it's not the custom properties any more (a browser restart fixed that) but on localghost.dev?theme=city trying to change the colour of the `[data-theme="city"] .content h1` is not working - I think it might be the data attribute?

Taaaaa! I've set a reminder to dig into this tomorrow morning.

If it helps, I've been nerd-sniped and it seems it's caused by the 🔗 emoji and the [] attribute selector on the same line: jsfiddle.net/3kmh058o/

Turns out it's not that emoji in particular, but any 4 byte character will repro.

Yep! And it doesn't need to be in a property value either. Fun one! Filed bugzilla.mozilla.org/show_bug.cgi...

Thanks @tristan-f.bsky.social for figuring out the cause, and thanks @localghost.dev for reporting!

The fix just landed, and should be in the next nightly bugzilla.mozilla.org/show_bug.cgi...