tailwindcss: "Can't resolve 'tailwindcss'" error occurs when attempting to build CSS file

[nint8835]

brew gist-logs <formula> link OR brew config AND brew doctor output

~/Development/issue-repro
❯ brew config
HOMEBREW_VERSION: 4.4.17
ORIGIN: https://github.com/Homebrew/brew
HEAD: 55f399c10dc7e6cc07497bdfccdecc96329e3b57
Last commit: 6 days ago
Branch: stable
Core tap JSON: 25 Jan 17:45 UTC
Core cask tap JSON: 25 Jan 17:45 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 3.3.7 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.3.7/bin/ruby
CPU: octa-core 64-bit arm_ibiza
Clang: 16.0.0 build 1600
Git: 2.39.5 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 15.2-arm64
CLT: 16.2.0.0.1.1733547573
Xcode: N/A
Rosetta 2: false

~/Development/issue-repro
❯ brew doctor
Your system is ready to brew.

Verification

• My brew doctor output says Your system is ready to brew. and am still able to reproduce my issue.
• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.
• I searched for recent similar issues at https://github.com/Homebrew/homebrew-core/issues?q=is%3Aissue and found no duplicates.

What were you trying to do (and why)?

I am attempting to use the version of the Tailwind CLI available through Homebrew to bundle a CSS file for my project using Tailwind. Since upgrading to V4, this no longer works. It does, however, work through the latest release of the CLI downloaded from their GitHub

What happened (include all command output)?

❯ tailwindcss -i index.css -o output.css
Error: Can't resolve 'tailwindcss' in '/Users/nint8835/Development/issue-repro'

What did you expect to happen?

I expected the file to build successfully, as occurs with the version of the Tailwind CLI file I downloaded from the GitHub release (https://github.com/tailwindlabs/tailwindcss/releases/tag/v4.0.0)

❯ ./tailwindcss-macos-arm64 -i index.css -o output.css
≈ tailwindcss v4.0.0

Done in 30ms

Step-by-step reproduction instructions (by running brew commands)

• Create a new directory to perform repro in

• Create an index.css containing the bare minimum to use Tailwind

  @import "tailwindcss";

• Install Tailwind via brew (brew install tailwindcss)

• Attempt to build your index.css (tailwindcss -i index.css -o output.css)

You should get the error Error: Can't resolve 'tailwindcss' in <current working directory>

• Download the latest release from Tailwind's repo (https://github.com/tailwindlabs/tailwindcss/releases/tag/v4.0.0) and repeat the same (./tailwindcss-macos-arm64 -i index.css -o output.css)

You should not get an error, and output.css should be generated successfully

I have had another person test this and confirm they were able to reproduce the same

[daeho-ro]

Is this still happen? My brand-new installation of tailwindcss is working good, no errors.

m4 pro 15.3

[nint8835]

Yes, still running into this

[DanielPower]

I can reproduce the error following the steps provided, with a fresh install of tailwindcss.

[branchvincent]

Thanks for the report, this looks like an upstream issue where the CLI assumes it can resolve the tailwindcss package from a node_modules folder in CWD/its parents (which isn't the case in a standard npm install -g installation like we do or even just via an isolated npx):

$ cd "$(mktemp -d)"
$ npx -p @tailwindcss/cli tailwindcss --watch
Error: Can't resolve 'tailwindcss' in ...

I assume this is unintentional. Their standalone binary uses different resolution logic and so isn't affected. Someone has already raised a discussion tailwindlabs/tailwindcss#15873 but I don't see a bug report yet

[nint8835]

I'm wondering if it makes sense to package their standalone binaries instead of doing a global install like is being done now? Not familiar with the packaging practices or policies of homebrew, but at least from testing it seems doing a global npm install of v3 still leaves me without the typography plugin able to be resolved, which was working in the version of v3 packaged by homebrew, and I'm not able to find any references to globally installing tailwind, so I'm wondering if doing a global install of tailwind's NPM package was ever properly supported by them

[cho-m]

The standalone CLI doesn't look like it will meet Homebrew's acceptable formula/cask requirements.

Formulae in homebrew/core cannot distribute pre-built binaries, should not use pre-built binaries during build, should not bundle other dependencies/runtime (which seems to be what Bun is used for), etc.

New casks in homebrew/cask require signed binaries:

❯ codesign --verify tailwindcss-macos-arm64
tailwindcss-macos-arm64: main executable failed strict validation

If you can get upstream to sign binaries, then can be considered for a new cask.