> I wish browser vendors could work around this limitation and stick to Sass syntax.
FWIW, it is not a limitation, it's a conscious choice. If you want to accept arbitrary selectors in option 3, you'll need unlimited lookahead, which limits the types of parser algorithms you can use, which means that _all CSS_ (not just CSS using nesting, every single web page out there) will be slower to parse, which means the web will become ever so slightly slower. And you cannot ever go back after making that choice. Is it really worth it for the few unusual cases that require workarounds, in an already not-super-common feature?
(Disclaimer: I wrote Chromium's CSS nesting support. It currently implements option 3.)
FWIW, it is not a limitation, it's a conscious choice. If you want to accept arbitrary selectors in option 3, you'll need unlimited lookahead, which limits the types of parser algorithms you can use, which means that _all CSS_ (not just CSS using nesting, every single web page out there) will be slower to parse, which means the web will become ever so slightly slower. And you cannot ever go back after making that choice. Is it really worth it for the few unusual cases that require workarounds, in an already not-super-common feature?
(Disclaimer: I wrote Chromium's CSS nesting support. It currently implements option 3.)