feature: native base layer

[Hugos68]

This PR moves our component styles from tailwind utilities to css, this allows us to move away from the skb layer and use the native @layer base directly, this has several benefits, notable ones are:

1. Remove @custom-variant skb (simplification)
2. Only ships utilities once instead of twice (skb: and non skb:)
3. Skip the build step and thus have instant hot reload during development
4. Simplify contributing, just write some css, no Tailwind-In-JS or imports/exports 😎
5. Tailwind intellisense without our previous hack

[changeset-bot]

🦋 Changeset detected

Latest commit: 5245df4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@skeletonlabs/skeleton-common	Patch
@skeletonlabs/skeleton-react	Patch
@skeletonlabs/skeleton-svelte	Patch
skeleton	Patch
@skeletonlabs/skeleton	Patch

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Project	Deployment	Preview	Updated (UTC)
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www.skeleton.dev	Ready	Preview	Dec 3, 2025 7:50pm

[Hugos68]

@copilot Inspect how I converted the accordion styles from the ts format to css, apply this to all components.

[Copilot]

@Hugos68 I've opened a new pull request, #4183, to work on those changes. Once the pull request is ready, I'll request review from you.

[Hugos68]

@copilot Now please remove all the imports from @skeletonlabs/skeleton-common/classes inside the component packages, you can remove that because the CSS is now imported seperately.

[Copilot]

@Hugos68 I've opened a new pull request, #4184, to work on those changes. Once the pull request is ready, I'll request review from you.

[endigo9740]

@Hugos68 everything looks good so far. The only thing of note here is that rewriting all our styles does mean we need to do a lot of manual regression testing. Even one small style being off could cause a regression. This will take more time than I have today. But we can continue to review over the next couple days as times allows.

[Hugos68]

Totally understand that. We need to be very thorough as there were already some instances where to due to specificity differences styles needed slight tweaking to behave like before. I already did a somewhat thorough pass, but you can never be sure enough.

[endigo9740]

@Hugos68 I've run through the checking styling for all these. There's two small issues to report, both visible on the Toast component docs page:

1. None of the examples are stacking vertically as multiple messages are queued (both frameworks)
2. The Overlap example has visible code showing (Svelte only; present in production too)

[Hugos68]

@endigo9740

None of the examples are stacking vertically as multiple messages are queued (both frameworks)

This was already the case, we can fix it in this PR though!

The Overlap example has visible code showing (Svelte only; present in production too)

I was not aware, will aim to fix 👍