Claude-skill-registry accessibility-a11y

Semantic HTML, keyboard navigation, focus states, ARIA labels, skip links, and WCAG contrast requirements. Use when ensuring accessibility compliance, implementing keyboard navigation, or adding screen reader support.

install

source · Clone the upstream repo

git clone https://github.com/majiayu000/claude-skill-registry

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/accessibility-a11y" ~/.claude/skills/majiayu000-claude-skill-registry-accessibility-a11y && rm -rf "$T"

manifest: skills/data/accessibility-a11y/SKILL.md

Accessibility (a11y)

Semantic HTML

// Use semantic elements
<header>       {/* Site header */}
<nav>          {/* Navigation */}
<main>         {/* Main content - one per page */}
<article>      {/* Self-contained content */}
<section>      {/* Thematic grouping with heading */}
<aside>        {/* Sidebar content */}
<footer>       {/* Site footer */}

// Correct heading hierarchy
<h1>Page Title</h1>           {/* One per page */}
  <h2>Section</h2>
    <h3>Subsection</h3>
  <h2>Another Section</h2>

// Lists for navigation
<nav>
  <ul>
    <li><a href="/">Home</a></li>
    <li><a href="/about">About</a></li>
  </ul>
</nav>

Skip Link

// components/layout/SkipLink.tsx
export function SkipLink() {
  return (
    <a
      href="#main-content"
      className="
        sr-only focus:not-sr-only
        focus:absolute focus:top-4 focus:left-4
        focus:z-50 focus:px-4 focus:py-2
        focus:bg-primary focus:text-primary-foreground
        focus:rounded
      "
    >
      Skip to main content
    </a>
  );
}

// In layout
<body>
  <SkipLink />
  <Header />
  <main id="main-content" tabIndex={-1}>
    {children}
  </main>
</body>

Focus Management

// Visible focus states (Tailwind)
<button className="
  focus:outline-none
  focus-visible:ring-2
  focus-visible:ring-ring
  focus-visible:ring-offset-2
">

// Focus trap for modals
import { useEffect, useRef } from 'react';

function useFocusTrap(isOpen: boolean) {
  const containerRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    if (!isOpen) return;
    
    const container = containerRef.current;
    if (!container) return;

    const focusableElements = container.querySelectorAll(
      'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
    );
    
    const firstElement = focusableElements[0] as HTMLElement;
    const lastElement = focusableElements[focusableElements.length - 1] as HTMLElement;

    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key !== 'Tab') return;

      if (e.shiftKey && document.activeElement === firstElement) {
        e.preventDefault();
        lastElement.focus();
      } else if (!e.shiftKey && document.activeElement === lastElement) {
        e.preventDefault();
        firstElement.focus();
      }
    };

    firstElement?.focus();
    container.addEventListener('keydown', handleKeyDown);
    
    return () => container.removeEventListener('keydown', handleKeyDown);
  }, [isOpen]);

  return containerRef;
}

ARIA Labels

// Buttons with icons only
<button aria-label="Close menu">
  <X className="w-5 h-5" />
</button>

// Loading states
<button disabled aria-busy="true">
  <Spinner aria-hidden="true" />
  <span>Submitting...</span>
</button>

// Live regions for dynamic content
<div aria-live="polite" aria-atomic="true">
  {statusMessage}
</div>

// Form errors
<input
  id="email"
  aria-invalid={hasError}
  aria-describedby={hasError ? 'email-error' : undefined}
/>
{hasError && (
  <p id="email-error" role="alert">
    Please enter a valid email
  </p>
)}

// Current page in navigation
<nav aria-label="Main navigation">
  <a href="/" aria-current={isHome ? 'page' : undefined}>Home</a>
  <a href="/about" aria-current={isAbout ? 'page' : undefined}>About</a>
</nav>

Keyboard Navigation

// Custom keyboard handlers
function handleKeyDown(e: React.KeyboardEvent) {
  switch (e.key) {
    case 'Enter':
    case ' ':
      e.preventDefault();
      handleSelect();
      break;
    case 'Escape':
      handleClose();
      break;
    case 'ArrowDown':
      e.preventDefault();
      focusNext();
      break;
    case 'ArrowUp':
      e.preventDefault();
      focusPrevious();
      break;
  }
}

// Roving tabindex for menu items
function MenuItem({ isSelected, ...props }) {
  return (
    <button
      role="menuitem"
      tabIndex={isSelected ? 0 : -1}
      {...props}
    />
  );
}

Color Contrast

// WCAG AA requirements:
// - Normal text: 4.5:1 ratio
// - Large text (18px+ or 14px+ bold): 3:1 ratio
// - UI components: 3:1 ratio

// Use contrast-safe color combinations
// ✅ Good
<p className="text-foreground bg-background">       {/* High contrast */}
<p className="text-muted-foreground bg-background"> {/* Adequate for large text */}

// ❌ Avoid
<p className="text-gray-400 bg-gray-100">           {/* Poor contrast */}

// Test with browser DevTools → Accessibility panel

Screen Reader Text

// Visually hidden but announced
<span className="sr-only">
  Opens in new tab
</span>

// Icon with hidden label
<a href="/facebook" aria-label="Facebook">
  <Facebook aria-hidden="true" />
</a>

// Decorative images
<img src="/decoration.svg" alt="" aria-hidden="true" />

// Meaningful images
<img src="/team.jpg" alt="Our team of certified instructors" />

Form Accessibility

// Complete accessible form
<form onSubmit={handleSubmit} aria-labelledby="form-title">
  <h2 id="form-title">Contact Us</h2>
  
  <div>
    <label htmlFor="name">
      Name <span aria-hidden="true">*</span>
      <span className="sr-only">(required)</span>
    </label>
    <input
      id="name"
      name="name"
      type="text"
      required
      aria-required="true"
      aria-invalid={errors.name ? 'true' : 'false'}
      aria-describedby={errors.name ? 'name-error' : 'name-hint'}
    />
    <p id="name-hint" className="text-sm text-muted-foreground">
      Enter your full name
    </p>
    {errors.name && (
      <p id="name-error" role="alert" className="text-destructive">
        {errors.name}
      </p>
    )}
  </div>
  
  <button type="submit">
    Submit
  </button>
</form>

Accordion Accessibility

// Accessible accordion pattern
function Accordion({ items }) {
  const [openIndex, setOpenIndex] = useState<number | null>(null);

  return (
    <div>
      {items.map((item, index) => (
        <div key={index}>
          <h3>
            <button
              id={`accordion-header-${index}`}
              aria-expanded={openIndex === index}
              aria-controls={`accordion-panel-${index}`}
              onClick={() => setOpenIndex(openIndex === index ? null : index)}
              className="w-full text-left"
            >
              {item.title}
            </button>
          </h3>
          <div
            id={`accordion-panel-${index}`}
            role="region"
            aria-labelledby={`accordion-header-${index}`}
            hidden={openIndex !== index}
          >
            {item.content}
          </div>
        </div>
      ))}
    </div>
  );
}

Reduced Motion

// Respect user preferences
import { useReducedMotion } from 'framer-motion';

function AnimatedComponent() {
  const shouldReduceMotion = useReducedMotion();

  return (
    <motion.div
      animate={{ y: 0, opacity: 1 }}
      transition={{
        duration: shouldReduceMotion ? 0 : 0.5,
      }}
    >
      Content
    </motion.div>
  );
}

// CSS approach
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

Testing Checklist

Navigate entire site with keyboard only (Tab, Enter, Escape, Arrows)
Test with screen reader (VoiceOver, NVDA)
Check color contrast ratios
Verify focus indicators are visible
Test at 200% zoom
Check heading hierarchy
Verify form labels and error messages
Test with reduced motion preference