@[email protected]

It’s not “Firefox-only” per se, it’s CSS. Firefox is fast when it comes to implementing updates that benefits multilingual and Asian support, and Chromium is either slow, implements a small part only, or just ignores it completely.

(aside: Another good example is Ruby annotation. Firefox’s implementation of Ruby is up-to-date while Chromium’s stuck in 2010.

And this is very very annoying, you have to design for Chromium when it comes to Ruby annotations; or use JavaScript to serve different Ruby codes per browser. Chromium is practically the “modern IE6”.)

It’s the same with :lang().

In Chromium, you still have to do it like this:

:lang(en-GB), :lang(en-US), :lang(en-AU), :lang(en-NZ), :lang(en-PH) { }  

In Firefox you can do it this way:

:lang(en-GB, en-US, en-AU, en-NZ, en-PH) { }  

or

:lang("en-GB", "en-US", "en-AU", "en-NZ", "en-PH") { }  

Another example, in Chromium:

:lang(ceb-Tglg), :lang(pam-Tglg), :lang(fil-Tglg) { }

:lang(ceb-Hano), :lang(pam-Hano), :lang(fil-Hano) { }  

In Firefox:

:lang(\*-Tglg) { }  
:lang(\*-Hano) { }  

or

:lang("*-Tglg) { }  
:lang("*-Hano) { }  

^_~