Accessibility

This skill makes interfaces usable by everyone — keyboard-only users, screen-reader users, low-vision users — and meets the legal bar (the EU Accessibility Act and ADA Title II both reference WCAG). Accessibility is not a nice-to-have; it's increasingly a legal requirement and always a larger addressable market.

Analogy: a curb cut was built for wheelchairs, but everyone with a stroller, suitcase, or bike uses it. Accessible UI is the same — built for those who need it, better for everyone.

Dependencies

This skill is stronger when Vercel's web-design-guidelines skill (part of vercel-labs/agent-skills, ~27k⭐) is installed — it ships the ARIA/focus/keyboard checklist. Delegate the checklist to it when present; always pair with the axe-core test step below, which catches runtime violations a static checklist can't. Never block on a missing dependency — the rules below are the embedded fallback.

The target

WCAG 2.2 Level AA — the bar referenced by the EU EAA, ADA Title II, and Section 508. Automated tools catch only ~30-40% of issues, so combine automated tests with manual checks.

Discovery (max 3 questions, only if unknown)

1. Are you building new components or auditing existing UI?
2. Any specific complaint (keyboard trap, unreadable contrast, screen reader silent)?
3. Is there a CI pipeline where an a11y test could run?

Step 1 — Semantic HTML first

Use native elements before ARIA: <button>, <nav>, <main>, <label>, <a>. "No ARIA is better than bad ARIA" — reach for ARIA only when no native element fits. Maintain a logical heading hierarchy (one <h1>, no skipped levels) and add a "skip to content" link.

Step 2 — Keyboard & focus

• Every interactive element reachable and operable by keyboard alone (Tab / Shift-Tab / Enter / Space / Esc). Test by unplugging the mouse.
• Never remove focus outlines without a replacement. Style :focus-visible instead of outline: none.
• No keyboard traps — focus must be able to leave any widget (modals: trap within while open, release on close).

Step 3 — Forms

• Every input has a programmatically associated <label> (or aria-label).
• Link errors with aria-describedby + set aria-invalid on the field.
• Don't rely on color alone to signal errors — add text/icon.

Step 4 — Color & targets

• Contrast ≥ 4.5:1 for normal text, ≥ 3:1 for large text and UI components/focus indicators.
• Touch targets ≥ 24×24px (WCAG 2.2 SC 2.5.8); 44×44px recommended for primary actions.

Step 5 — Dynamic content & motion

• Announce async updates (toasts, validation, loading) with an aria-live="polite" region.
• Honor prefers-reduced-motion — gate non-essential animation behind it (also a WCAG 2.3.3 requirement). Coordinate with the ui-design motion settings.

Step 6 — Test it

• Add jest-axe and assert per component: expect(await axe(container)).toHaveNoViolations(). Run it in CI.
• Manually test one full flow with a real screen reader (VoiceOver on macOS, NVDA on Windows) — automated tools can't judge whether the announced experience makes sense.

Output

Deliver: the accessible components (semantic markup, labels, focus handling), the contrast/target fixes, an aria-live region for dynamic status, and a jest-axe test wired into CI.

Reference

w3c/wcag (WCAG 2.2), dequelabs/axe-core (~7k⭐), nickcolley/jest-axe, vercel-labs/agent-skills web-design-guidelines.