Tailwind v4 Styles Missing in Development Mode on Windows Local Environment

[Newmcpe]

I'm encountering an issue while running a project locally with Tailwind CSS v4. The project functions correctly on *nix-like systems and in production. However, in development mode on Windows 11, Tailwind styles are not being applied to the site. Could you advise on where I should investigate to resolve this issue?

my postcss config https://yaso.su/9SkrQEyi
nextjs config https://yaso.su/xJ4gJZak
packagejson https://yaso.su/Fc4FwVQM
tsconfig https://yaso.su/YNSECYQe
global.css https://yaso.su/NHsHFnUj

[Drako01]

Since the same project works on Unix-like systems and in production, I would first investigate environment-specific build configuration rather than changing the Tailwind utility classes.

For Tailwind CSS v4, I'd check these areas in order.

1. Verify the PostCSS integration

Make sure the project uses @tailwindcss/postcss, not the old Tailwind v3 PostCSS configuration:

export default {
  plugins: {
    "@tailwindcss/postcss": {},
  },
}

Your CSS entry should include:

@import "tailwindcss";

2. Check source detection

Tailwind v4 automatically scans project files, but monorepo layouts and different working directories can affect which files are discovered.

If your development command starts from a different directory on Windows, try making the source path explicit:

@import "tailwindcss" source("../src");

Adjust the path relative to your stylesheet.

3. Isolate the CSS compiler

Run a direct Tailwind CLI build and inspect the resulting CSS.

If the expected classes are generated by the CLI but missing from the browser, the problem is probably in the Next.js/PostCSS integration or CSS import path.

If they're missing from the generated CSS, focus on source detection and class-name construction.

4. Compare runtime environments

Check:

• Node.js version.
• Package manager and lockfile.
• Tailwind and PostCSS package versions.
• Working directory.
• CSS import location.
• Cached build artifacts.

I would also remove the local .next cache before retesting.

One thing to avoid: reverting to Tailwind v3 directives (@tailwind base, @tailwind components, @tailwind utilities) while keeping the v4 toolchain.

If you can share the actual PostCSS config and CSS entry point as text, it should be possible to narrow this down quickly.