Should we allow !important decls in @position-try? I'm inclined to say no - we're already having to do some slightly odd things with the cascade to make things work reasonably well and in a well-defined way (particularly with flip-* keywords), so having some parts of the rule also apply in a separate !important location would make it a lot more complicated for little, if any, benefit to authors.

(And, like, where exactly would they go anyway? We resolved that normal decls here go at "the end of the author origin", and I'm inclined to actually specify that as a separate origin placed right after Author. Whether an "important position-try decl" should follow normal origin-reversing order (being weaker than author !important rules) or violate that to still go after the author !important rules would be an important decision, and both options are fairly bad, I think.)

So, propose to disallow !important.