chore(deps): update dependency tailwindcss to v4

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
tailwindcss (source)	3.4.17 -> 4.0.0

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Release Notes

tailwindlabs/tailwindcss (tailwindcss)

v4.0.0

Compare Source

Added

• New high-performance engine — where full builds are up to 5x faster, and incremental builds are over 100x faster — and measured in microseconds.
• Designed for the modern web — built on cutting-edge CSS features like cascade layers, registered custom properties with @property, and color-mix().
• Simplified installation — fewer dependencies, zero configuration, and just a single line of code in your CSS file.
• First-party Vite plugin — tight integration for maximum performance and minimum configuration.
• Automatic content detection — all of your template files are discovered automatically, with no configuration required.
• Built-in import support — no additional tooling necessary to bundle multiple CSS files.
• CSS-first configuration — a reimagined developer experience where you customize and extend the framework directly in CSS instead of a JavaScript configuration file.
• CSS theme variables — all of your design tokens exposed as native CSS variables so you can access them anywhere.
• Dynamic utility values and variants — stop guessing what values exist in your spacing scale, or extending your configuration for things like basic data attributes.
• Modernized P3 color palette — a redesigned, more vivid color palette that takes full advantage of modern display technology.
• Container queries — first-class APIs for styling elements based on their container size, no plugins required.
• New 3D transform utilities — transform elements in 3D space directly in your HTML.
• Expanded gradient APIs — radial and conic gradients, interpolation modes, and more.
• @​starting-style support — a new variant you can use to create enter and exit transitions, without the need for JavaScript.
• not-* variant — style an element only when it doesn't match another variant, custom selector, or media or feature query.
• Even more new utilities and variants — including support for color-scheme, field-sizing, complex shadows, inert, and more.

Start using Tailwind CSS v4.0 today by installing it in a new project, or playing with it directly in the browser on Tailwind Play.

For existing projects, we've published a comprehensive upgrade guide and built an automated upgrade tool to get you on the latest version as quickly and painlessly as possible.

For a deep-dive into everything that's new, check out the announcement post.

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Configuration

📅 Schedule: Branch creation - "every weekend" in timezone Europe/Amsterdam, Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• If you want to rebase/retry this PR, check this box

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[hugo-vrijswijk]

Needs tailwindlabs/tailwindcss#15799 to be fixed first.

After that:

• Run migration tool
• Check if cssnano still has benefit, otherwise postcss can be completely removed and just use the tailwind vite plugin
• Look at theme colours css variables. Potentially they could all be defined in tailwind.css
• Look at new oklch colour space for colours (and use updated tailwind colours)
• Make sure screenshot tests pass and look the same

[renovate]

Edited/Blocked Notification

Renovate will not automatically rebase this PR, because it does not recognize the last commit author and assumes somebody else may have edited the PR.

You can manually request rebase by checking the rebase/retry box above.

⚠️ Warning: custom changes will be lost.

[bundlemon]

BundleMon (elements)

Files updated (3)

Status	Path	Size	Limits
✅	index.js	295.25KB (+19.82KB +7.2%)	-
✅	mutation-test-elements.js	239.31KB (+19.79KB +9.02%)	-
✅	index.cjs	221.04KB (+19.78KB +9.83%)	-

Total files change +59.4KB +8.53%

Final result: ✅

View report in BundleMon website ➡️

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Current branch size history | Target branch size history