[css-2023] Add !important tiers, such as !important-1, !important-10 like z-indexes

[alexluongfm]

Add !important tiers to easily allow overriding higher level css with local changes. Where !important would default to !important-1 and higher tiers override lower ones just like z indexes.

More of a quality of life/making life easier change.

[cdoublev]

Don't you think that !important is often considered as a "code smell" that can now be avoided with @layer and @scope? And you can still increase the specificity of the selector whose declaration should be more important.

[tabatkins]

!important, in general, shouldn't be heavily used. The @layer rule is the intended way to handle the sort of specificity conflicts that caused people to overuse !important in the past.