typo3-tailwind-migration

name

typo3-tailwind-migration

description

Migrate a TYPO3 theme from legacy/custom CSS to Tailwind CSS v4 in a DDEV environment. Use this skill when a TYPO3 project needs to convert its existing CSS-based site package to Tailwind utility classes while maintaining 1:1 visual parity. Covers the complete workflow from visual regression baseline capture through build pipeline setup, design token mapping, Fluid template migration, content element conversion, accessibility auditing, and cross-browser verification. Critical emphasis on regression-test-first approach — always capture baselines before any migration work begins.

TYPO3 Tailwind CSS Migration

Migrate an existing TYPO3 site package from legacy/custom CSS to Tailwind CSS v4 within a DDEV development environment. This skill encapsulates battle-tested learnings from a complete migration project.

Most important lesson: Set up VRT baselines and the test environment in the first sprint, not the last. Capture the legacy site's appearance before touching any CSS. Every migration decision is verified against these baselines.

Migration Workflow

Follow these 6 phases in strict order:

Phase 0: Pre-Flight — VRT Baseline & Test Environment

⚠️ MANDATORY FIRST STEP. Do NOT skip or defer this.

1. Set up Playwright inside the TYPO3 site package (see the companion skill typo3-playwright-ddev for detailed DDEV setup)
2. Create visual regression tests for every page layout and every content element in the legacy site
3. Run ddev exec "cd packages/[theme-name] && npx playwright test --update-snapshots" to generate baseline screenshots
4. Commit the baselines — these are the "source of truth" for the entire migration

Test file checklist:

• One .spec.ts per page layout (e.g., Default, Homepage, Sidebar — whatever your project defines)
• One .spec.ts for all content elements on a dedicated test page
• Verify every .spec.ts file is committed (Epic 1 lesson: missing test files = silent coverage gaps)

See references/migration-checklist.md for the complete pre-flight checklist.

Phase 1: Foundation — Build Pipeline & Design Tokens

1. Install Tailwind CSS v4 dependencies:

   ddev npm install --save-dev tailwindcss postcss @tailwindcss/postcss postcss-cli cssnano
   

2. Create the build pipeline — see references/build-pipeline.md for:

   • postcss.config.js setup
   • CSS entry point with @import "tailwindcss" (v4 syntax)
   • Content scanning paths for TYPO3 Fluid templates
   • npm scripts for dev/build

3. Map existing design tokens to Tailwind @theme block — see references/design-tokens.md for:

   • Color palette mapping
   • Typography (fonts, weights)
   • Spacing scale
   • Border radius
   • Breakpoints

4. Verify integration in a Fluid template:

   • Add a test class like bg-primary-100 to any element
   • Run ddev npm run build
   • Confirm the class renders correctly in the browser

Phase 2: Layouts & Global Partials

Migrate page layouts and global components in this order:

1. Page Layouts (migrate each layout defined in your site package, one at a time)

   • Replace legacy CSS classes with Tailwind utilities
   • Use f:asset.css to load the compiled main.css
   • Verify against Phase 0 baselines after each layout

2. Header & Navigation

   • Sticky header: sticky top-0 z-50
   • Mobile-first: base styles for mobile, md: prefix for desktop
   • Burger menu: semantic <button> with aria-expanded, aria-controls, aria-label
   • JavaScript toggle in a single consolidated main.js (avoid dead code in separate files)

3. Footer

   • CMS-first: Use lib.dynamicContent or Menu Processor — NOT TypoScript settings
   • Responsive stacking: vertical on mobile, horizontal on desktop

See references/fluid-integration.md for TYPO3-specific Fluid + Tailwind patterns.

Phase 3: Content Elements

Migrate each content element type:

1. Text — typography (H1-H6, p, lists), heading hierarchy
2. Image — responsive sizing, alt text, loading="eager" for hero/LCP images
3. Text + Image (Textpic) — grid layout with orientation fallbacks (above/below/left/right), mobile stacking
4. Hero — diagonal split via clip-path, CTA button styling, mobile legibility
5. Secondary/Sidebar content — if your project has multi-column layouts, pass colPos from page layout through all partial layers to enable context-aware styling (smaller headings, adjusted image sizes)

After each content element:

• Run ddev exec "cd packages/[theme-name] && npx playwright test --grep @stitch-vrt" to compare against Phase 0 baselines
• Extract margins/paddings from baseline screenshots — do NOT guess spacing values
• Fix any diffs before proceeding to the next element

See references/migration-checklist.md for the element-by-element checklist.

Phase 4: Quality Assurance

1. Visual Regression Verification

   • Run full VRT suite: ddev exec "cd packages/[theme-name] && npx playwright test --grep @stitch-vrt"
   • Target: 0 deviations from Phase 0 baselines
   • Document and justify any intentional changes

2. Accessibility Audit

   • Integrate @axe-core/playwright into the test suite
   • Verify WCAG 2.1 AA compliance across all layouts
   • Verify all theme variants (if applicable) for color contrast
   • Check: Skip-to-content link, lang attribute on <html>, focus indicators

3. Cross-Browser Testing

   • Functional tests in Chromium, Firefox, WebKit
   • Console error monitoring (filter DDEV benign patterns)
   • Run cross-browser smoke tests after every story, not just at project end

4. Performance

   • CSS bundle < 100KB compressed (Tailwind purge does most of the work)
   • Verify loading="eager" on LCP images
   • Optimize in the build pipeline, not in CMS runtime logic

Phase 5: Cleanup

1. Remove legacy CSS files (keep backups until fully verified)
2. Run ddev npm run build — verify final main.css contains only used utilities
3. Run full test suite one final time
4. Update project documentation

Anti-Patterns & Critical Gotchas

For the complete list of pitfalls discovered during the original migration, see references/anti-patterns.md. The top 5:

1. Never blindly --update-snapshots — every VRT diff must be understood and justified
2. Never defer test environment setup — set up Playwright+DDEV in Phase 0, not Phase 4
3. Never hardcode CMS content — Footer, navigation, and dynamic sections must use TYPO3's content APIs
4. Never guess spacing — extract margins/paddings from baseline screenshots or UX specs
5. Never install Playwright on host — always use ddev exec "npx playwright install" (Linux container ≠ macOS)

Quality Gates

Gate	When	Rule
Test file verification	Every code review	Every .spec.ts must be committed; snapshots must have matching spec files
VRT comparison	After every component	Compare against Phase 0 baselines, not newly generated snapshots
A11y audit	After layout completion	Run axe-core across all viewports and theme variants
Cross-browser smoke	After every story	Don't wait until the final epic
Spacing verification	Before marking "done"	Compare pixel-level spacing against baseline screenshots