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Tailwind Validator by shipshitdev — Agent Skill

Name: Tailwind Validator
Author: shipshitdev

Tailwind Validator

Validate Tailwind CSS v4 configuration and detect/prevent Tailwind v3 patterns. Use this skill when setting up Tailwind, auditing CSS configuration, or when you suspect outdated Tailwind patterns are being used. Ensures CSS-first configuration with @theme blocks.

shipshitdev Updated Sep 21, 2026

File contents

Tailwind 4 Validator

Purpose

Ensures:

Projects use Tailwind v4 CSS-first configuration
Old tailwind.config.js patterns are detected and flagged
Proper @theme blocks are used instead of JS config
Dependencies are v4+

When to Use

Before any Tailwind work: Run validation first
New project setup: Ensure v4 is installed correctly
After AI generates Tailwind code: Verify no v3 patterns snuck in
Auditing existing projects: Check for migration needs
CI/CD pipelines: Prevent v3 regressions

Quick Start

python3 scripts/validate.py --root .
python3 scripts/validate.py --root . --suggest-fixes
python3 scripts/validate.py --root . --strict

What Gets Checked

Check	Good (v4)	Bad (v3)
Package version	`"tailwindcss": "^4.0.0"`	`"^3.4.0"`
CSS config	`@import "tailwindcss";` + `@theme { --color-primary: ...; }`	`@tailwind base/components/utilities;`
Config files	none - config lives in CSS	`tailwind.config.{js,ts,mjs,cjs}` (deprecated in v4)
PostCSS	`plugins: { '@tailwindcss/postcss': {} }` only	`tailwindcss` + `autoprefixer` as separate plugins
Imports	`@import "tailwindcss/preflight"` / `.../utilities`	`@tailwind` directives

See references/full-guide.md (§ What Gets Checked, § Validation Output) for full GOOD/BAD examples and a sample validation report.

Migration Guide (v3 to v4)

Swap packages: remove tailwindcss/autoprefixer, add tailwindcss@latest + @tailwindcss/postcss
Point postcss.config.js at the @tailwindcss/postcss plugin only
Convert tailwind.config.js theme/extend values into an @theme { --color-*, --font-*, ... } block in CSS
Replace @tailwind directives with @import "tailwindcss"
Delete tailwind.config.{js,ts,mjs,cjs}

See references/full-guide.md (§ Migration Guide, § CI/CD Integration) for the exact before/after code per step and a CI workflow snippet.

Common v3 Patterns to Avoid

v3 Pattern	v4 Replacement
`@tailwind base`	`@import "tailwindcss"`
`@tailwind utilities`	`@import "tailwindcss/utilities"`
`tailwind.config.js`	`@theme` block in CSS
`theme.extend.colors`	`--color-*` CSS variables
`theme.extend.spacing`	`--spacing-*` CSS variables
`theme.extend.fontFamily`	`--font-*` CSS variables
`content: ['./src/*/.tsx']`	Not needed (auto-detected)
`plugins: [require('@tailwindcss/forms')]`	`@plugin "@tailwindcss/forms"`

See references/full-guide.md (§ v4 @theme Reference, § Using with shadcn/ui) for a full @theme token example and shadcn/ui token setup.

Troubleshooting

"Found tailwind.config.js but using v4" - some tools still generate v3 configs. Delete the file and use @theme instead.
"@tailwind directives found" - replace with @import "tailwindcss". The old directives are not supported in v4.
"autoprefixer in postcss.config" - remove autoprefixer; it's built into @tailwindcss/postcss.
"content array in config" - v4 auto-detects content files. Remove the content config entirely.

---name: tailwind-validator-3description: Validate Tailwind CSS v4 configuration and detect/prevent Tailwind v3 patterns. Use this skill when setting up Tailwind, auditing CSS configuration, or when you suspect outdated Tailwind patterns are being used. Ensures CSS-first configuration with @theme blocks.---# Tailwind 4 Validator## PurposeEnsures:- Projects use Tailwind v4 CSS-first configuration- Old `tailwind.config.js` patterns are detected and flagged- Proper `@theme` blocks are used instead of JS config- Dependencies are v4+## When to Use- **Before any Tailwind work**: Run validation first- **New project setup**: Ensure v4 is installed correctly- **After AI generates Tailwind code**: Verify no v3 patterns snuck in- **Auditing existing projects**: Check for migration needs- **CI/CD pipelines**: Prevent v3 regressions## Quick Start```bashpython3 scripts/validate.py --root .python3 scripts/validate.py --root . --suggest-fixespython3 scripts/validate.py --root . --strict```## What Gets Checked| Check | Good (v4) | Bad (v3) ||---|---|---|| Package version | `"tailwindcss": "^4.0.0"` | `"^3.4.0"` || CSS config | `@import "tailwindcss";` + `@theme { --color-primary: ...; }` | `@tailwind base/components/utilities;` || Config files | none - config lives in CSS | `tailwind.config.{js,ts,mjs,cjs}` (deprecated in v4) || PostCSS | `plugins: { '@tailwindcss/postcss': {} }` only | `tailwindcss` + `autoprefixer` as separate plugins || Imports | `@import "tailwindcss/preflight"` / `.../utilities` | `@tailwind` directives |See `references/full-guide.md` (§ What Gets Checked, § Validation Output) for full GOOD/BAD examples and a sample validation report.## Migration Guide (v3 to v4)1. Swap packages: remove `tailwindcss`/`autoprefixer`, add `tailwindcss@latest` + `@tailwindcss/postcss`2. Point `postcss.config.js` at the `@tailwindcss/postcss` plugin only3. Convert `tailwind.config.js` theme/extend values into an `@theme { --color-*, --font-*, ... }` block in CSS4. Replace `@tailwind` directives with `@import "tailwindcss"`5. Delete `tailwind.config.{js,ts,mjs,cjs}`See `references/full-guide.md` (§ Migration Guide, § CI/CD Integration) for the exact before/after code per step and a CI workflow snippet.## Common v3 Patterns to Avoid| v3 Pattern | v4 Replacement ||------------|----------------|| `@tailwind base` | `@import "tailwindcss"` || `@tailwind utilities` | `@import "tailwindcss/utilities"` || `tailwind.config.js` | `@theme` block in CSS || `theme.extend.colors` | `--color-*` CSS variables || `theme.extend.spacing` | `--spacing-*` CSS variables || `theme.extend.fontFamily` | `--font-*` CSS variables || `content: ['./src/**/*.tsx']` | Not needed (auto-detected) || `plugins: [require('@tailwindcss/forms')]` | `@plugin "@tailwindcss/forms"` |See `references/full-guide.md` (§ v4 @theme Reference, § Using with shadcn/ui) for a full `@theme` token example and shadcn/ui token setup.## Troubleshooting- **"Found tailwind.config.js but using v4"** - some tools still generate v3 configs. Delete the file and use `@theme` instead.- **"@tailwind directives found"** - replace with `@import "tailwindcss"`. The old directives are not supported in v4.- **"autoprefixer in postcss.config"** - remove autoprefixer; it's built into `@tailwindcss/postcss`.- **"content array in config"** - v4 auto-detects content files. Remove the `content` config entirely.

Frequently asked questions