TailwindCSS v4 build succeeds but changes/styles are not applied with importmap

[Elemtro]

Problem

When using importmap and TailwindCSS v4.0 with symfony/tailwind-bundle, the build command (tailwind:build or tailwind:build --watch) completes, but style changes are not applied in the browser. Classes are generated only in part (e.g., positioning classes) while others (like colors/components) are missing or not updated.

Related Discussion

Closed and ongoing issues suggest this may be caused by:

• Tailwind v4 breaking changes affecting config and scanning (see Tailwind upgrade guide)
• Tailwind v4 no longer auto-detects config files the same way as v3
• Users needing to update app.css to use @import "tailwindcss"; instead of legacy directives (@tailwind base; etc.)
• Some users report success by locking the CLI to v3.x in config/packages/symfonycasts_tailwind.yaml, while others have Tailwind v4 working with minor changes in app.css

Steps to Reproduce

1. Set up symfony/tailwind-bundle with importmap and TailwindCSS v4.0
2. Run tailwind:build or tailwind:build --watch
3. Observe that only some styles are output; others do not appear or update when editing templates

Screenshot

What I Tried

• Changed config and reverted bundle/cli version to v3: problem still persists
• Used Tailwind v4 with only config changes as suggested in community: partial success, not all styles generated
• Cleared old Tailwind caches in ./var/tailwind/*
• Updated app.css with new Tailwind v4 import and plugin directives

References

See discussions and experimental fixes in:

• Tailwind v4 Support #81

Expected Behavior

Styles and changes should be reflected after build just as with TailwindCSS v3.x, with importmap setup.

Actual Behavior

Partial or outdated styles; changes in templates not picked up by Tailwind v4 with the bundle. Build looks successful but results are not visible on page.

Environment

• Symfony 7.3 + importmap
• TailwindCSS v4.0.x
• symfony/tailwind-bundle latest
• Docker

Additional context

Tailwind's documentation for Symfony suggests using Webpack Encore, and I can confirm that this works perfectly. However, I want to use importmap as it is a best practice for modern Symfony applications, but it is not working. (see Tailwind install symfony)

Suggestions/Questions

• Is there an updated, working configuration for Tailwind v4 + importmap?
• Are any changes needed to the bundle to support the breaking changes, scan, or directives in Tailwind v4?
• Should the docs be updated to guide users for v4 compatibility?

---

If anyone has a working setup with importmap + Tailwind v4, please share the config details.