chore(tailwind): use @theme inline and add docs

[Barsnes]

Summary

resolves #4317

This was first generated by Claude, then modified and check by me.

Checks

• I have read the contribution guidelines
• I have added a changeset (run pnpm changeset if relevant)

[changeset-bot]

🦋 Changeset detected

Latest commit: 81b8221

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

This PR includes changesets to release 5 packages

Name	Type
@digdir/designsystemet	Patch
@digdir/designsystemet-css	Patch
@digdir/designsystemet-react	Patch
@digdir/designsystemet-types	Patch
@digdir/designsystemet-web	Patch

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[github-actions]

Preview deployments for this pull request:

storybook - 17. Sep 2026 - 09:41

www - 17. Sep 2026 - 09:42

[eirikbacker]

Fantastic PR! 🤗 Only one though; Tailwind v3 supports @theme but not @theme inline - should we have a config --tailwind=v3 or similar as well for backwards compatible export? 🤔

[Barsnes]

Fantastic PR! 🤗 Only one though; Tailwind v3 supports @theme but not @theme inline - should we have a config --tailwind=v3 or similar as well for backwards compatible export? 🤔

@mimarz needs to decide this

[mimarz]

Fantastic PR! 🤗 Only one though; Tailwind v3 supports @theme but not @theme inline - should we have a config --tailwind=v3 or similar as well for backwards compatible export? 🤔

@mimarz needs to decide this

I agreed with the config option, but lets look at it next week how we expose/enable this :)

[mimarz]

I will make a new PR where we enable the new output config field. When doing so I can pull tailwind out of experimental there, since building the current way (using tokens build) will be deprecated.