Class conflicts in Shell.Cn aren't resolved (tailwind-merge) #51

Summary

Shell.Cn joins class strings but doesn't resolve Tailwind conflicts, so a consumer's Class can't reliably override a component's default. Class="max-w-2xl" on a component that already has max-w-sm leaves both classes, and which one wins depends on the order in the generated CSS, not on the order written.

Steps to reproduce

<SheetContent Class="sm:max-w-2xl">...</SheetContent>

Expected: the sheet is max-w-2xl wide.
Actual: it stays max-w-sm. The workaround today is Tailwind's important modifier (sm:max-w-2xl!).

Suggested fix

Port the core of tailwind-merge to Shell.Cn: group utilities by what they set (max-w-*, p-*/px-*, colours, …) including variants (sm:, hover:), and keep the last class in each group. Start with the groups components set by default (sizing, spacing, colours, borders, radius) and cover them with unit tests.