accessibility-patterns

Build inclusive web experiences following WCAG guidelines. Covers semantic HTML, ARIA, keyboard navigation, color contrast, and testing strategies. Triggers on accessibility, a11y, WCAG, screen readers, or inclusive design requests.

5 stars

byorganvm-iv-taxis

View on GitHub Installation ↓

Best use case

accessibility-patterns is best used when you need a repeatable AI agent workflow instead of a one-off prompt.

Teams using accessibility-patterns should expect a more consistent output, faster repeated execution, less prompt rewriting.

When to use this skill

You want a reusable workflow that can be run more than once with consistent structure.

When not to use this skill

You only need a quick one-off answer and do not need a reusable workflow.
You cannot install or maintain the underlying files, dependencies, or repository context.

Installation

Claude Code / Cursor / Codex

$curl -o ~/.claude/skills/accessibility-patterns/SKILL.md --create-dirs "https://raw.githubusercontent.com/organvm-iv-taxis/a-i--skills/main/distributions/claude/skills/accessibility-patterns/SKILL.md"

Manual Installation

Download SKILL.md from GitHub
Place it in .claude/skills/accessibility-patterns/SKILL.md inside your project
Restart your AI agent — it will auto-discover the skill

How accessibility-patterns Compares

Feature / Agent	accessibility-patterns	Standard Approach
Platform Support	Not specified	Limited / Varies
Context Awareness	High	Baseline
Installation Complexity	Unknown	N/A

Frequently Asked Questions

What does this skill do?

Where can I find the source code?

You can find the source code on GitHub using the link provided at the top of the page.

SKILL.md Source

# Accessibility Patterns

Build for everyone from the start.

## Core Principles (POUR)

| Principle | Meaning | Example |
|-----------|---------|---------|
| **Perceivable** | Users can perceive content | Alt text, captions, contrast |
| **Operable** | Users can interact | Keyboard access, enough time |
| **Understandable** | Users can comprehend | Clear language, predictable |
| **Robust** | Works with assistive tech | Valid HTML, ARIA |

---

## WCAG Levels

| Level | Description | Target |
|-------|-------------|--------|
| A | Minimum | Must have |
| AA | Standard | Industry standard, legal requirement |
| AAA | Enhanced | Nice to have |

**Target Level AA** for most projects.

---

## Semantic HTML

### Use the Right Element

| Instead of | Use |
|------------|-----|
| `<div onclick>` | `<button>` |
| `<span class="link">` | `<a href>` |
| `<div class="header">` | `<header>` |
| `<div class="nav">` | `<nav>` |
| `<div class="main">` | `<main>` |
| `<b>` for emphasis | `<strong>` |
| `<i>` for emphasis | `<em>` |

### Document Structure

```html
<!DOCTYPE html>
<html lang="en">
<head>
  <title>Descriptive Page Title</title>
</head>
<body>
  <a href="#main" class="skip-link">Skip to main content</a>
  
  <header>
    <nav aria-label="Main">
      <!-- navigation -->
    </nav>
  </header>
  
  <main id="main">
    <h1>Page Title</h1>
    <!-- Only one h1 per page -->
    
    <article>
      <h2>Section</h2>
      <h3>Subsection</h3>
    </article>
  </main>
  
  <aside aria-label="Related content">
    <!-- sidebar -->
  </aside>
  
  <footer>
    <!-- footer content -->
  </footer>
</body>
</html>
```

### Heading Hierarchy

```
h1 - Page title (one per page)
  h2 - Major sections
    h3 - Subsections
      h4 - Sub-subsections

Never skip levels (h1 → h3)
```

---

## Images & Media

### Alt Text

```html
<!-- Informative image -->
<img src="chart.png" alt="Bar chart showing sales increased 40% in Q4">

<!-- Decorative image -->
<img src="decorative-border.png" alt="" role="presentation">

<!-- Complex image -->
<figure>
  <img src="complex-diagram.png" alt="System architecture diagram">
  <figcaption>
    Detailed description of the system architecture...
  </figcaption>
</figure>

<!-- Image as link -->
<a href="/products">
  <img src="product.jpg" alt="View our products">
</a>
```

### Alt Text Guidelines

| Image Type | Alt Text Strategy |
|------------|-------------------|
| Informative | Describe content and function |
| Decorative | Empty alt="" |
| Functional | Describe the action |
| Complex | Brief alt + longer description |
| Text in image | Include all text |

### Video & Audio

```html
<!-- Video with captions -->
<video controls>
  <source src="video.mp4" type="video/mp4">
  <track kind="captions" src="captions.vtt" srclang="en" label="English">
  <track kind="descriptions" src="descriptions.vtt" srclang="en" label="Audio descriptions">
</video>

<!-- Audio with transcript -->
<audio controls>
  <source src="podcast.mp3" type="audio/mpeg">
</audio>
<a href="transcript.html">Read transcript</a>
```

---

## Forms

### Labels

```html
<!-- Explicit label (preferred) -->
<label for="email">Email address</label>
<input type="email" id="email" name="email">

<!-- Implicit label -->
<label>
  Email address
  <input type="email" name="email">
</label>

<!-- Required fields -->
<label for="name">
  Name <span aria-hidden="true">*</span>
  <span class="sr-only">(required)</span>
</label>
<input type="text" id="name" required aria-required="true">
```

### Error Handling

```html
<div role="alert" aria-live="polite">
  <p>Please fix the following errors:</p>
  <ul>
    <li><a href="#email">Email is required</a></li>
  </ul>
</div>

<label for="email">Email</label>
<input 
  type="email" 
  id="email" 
  aria-invalid="true"
  aria-describedby="email-error"
>
<span id="email-error" class="error">Please enter a valid email address</span>
```

### Form Groups

```html
<fieldset>
  <legend>Shipping Address</legend>
  
  <label for="street">Street</label>
  <input type="text" id="street">
  
  <label for="city">City</label>
  <input type="text" id="city">
</fieldset>
```

---

## Keyboard Navigation

### Focus Management

```css
/* Never remove focus outline without replacement */
:focus {
  outline: 2px solid #005fcc;
  outline-offset: 2px;
}

/* Custom focus style */
:focus-visible {
  outline: 3px solid #005fcc;
  outline-offset: 2px;
}

/* Hide outline for mouse users */
:focus:not(:focus-visible) {
  outline: none;
}
```

### Tab Order

```html
<!-- Natural tab order follows DOM order -->
<!-- Use tabindex only when necessary -->

<button>First</button>
<button>Second</button>
<button>Third</button>

<!-- tabindex="0" - adds to tab order -->
<div tabindex="0" role="button">Custom interactive element</div>

<!-- tabindex="-1" - focusable via JS, not tab -->
<div tabindex="-1" id="modal">Modal content</div>

<!-- Never use tabindex > 0 -->
```

### Skip Links

```html
<a href="#main" class="skip-link">Skip to main content</a>

<style>
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  padding: 8px;
  background: #000;
  color: #fff;
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}
</style>
```

### Keyboard Patterns

| Component | Keys |
|-----------|------|
| Buttons | Enter, Space |
| Links | Enter |
| Menus | Arrows, Enter, Escape |
| Tabs | Arrows, Tab |
| Modals | Tab (trapped), Escape to close |

---

## ARIA

### When to Use ARIA

1. First, use semantic HTML
2. Then, add ARIA if needed
3. "No ARIA is better than bad ARIA"

### Common ARIA Patterns

```html
<!-- Live regions (for dynamic content) -->
<div aria-live="polite">Content updates will be announced</div>
<div aria-live="assertive">Urgent updates interrupt</div>

<!-- Expanded/collapsed -->
<button aria-expanded="false" aria-controls="menu">Menu</button>
<ul id="menu" hidden>...</ul>

<!-- Current page -->
<nav>
  <a href="/" aria-current="page">Home</a>
  <a href="/about">About</a>
</nav>

<!-- Busy state -->
<div aria-busy="true">Loading...</div>

<!-- Hidden from AT -->
<span aria-hidden="true">👍</span>

<!-- Labels -->
<button aria-label="Close">×</button>
<nav aria-label="Main navigation">...</nav>
<section aria-labelledby="section-heading">
  <h2 id="section-heading">Section Title</h2>
</section>
```

### ARIA Roles

```html
<!-- Landmarks -->
<div role="banner">Header</div>
<div role="navigation">Nav</div>
<div role="main">Main</div>
<div role="complementary">Sidebar</div>
<div role="contentinfo">Footer</div>

<!-- Widgets -->
<div role="button">Custom button</div>
<div role="dialog" aria-modal="true">Modal</div>
<div role="tablist">Tabs</div>
<div role="alert">Error message</div>
```

---

## Color & Contrast

### Contrast Requirements

| Text Size | Level AA | Level AAA |
|-----------|----------|-----------|
| Normal text (<18px) | 4.5:1 | 7:1 |
| Large text (≥18px bold, ≥24px) | 3:1 | 4.5:1 |
| UI components | 3:1 | - |

### Color Independence

```html
<!-- Don't rely on color alone -->

<!-- Bad -->
<span style="color: red">Error</span>

<!-- Good -->
<span style="color: red">
  ⚠️ Error: <span class="error-text">Please enter a valid email</span>
</span>
```

### Testing Tools

- WebAIM Contrast Checker
- Chrome DevTools color picker
- Stark (Figma plugin)
- axe DevTools

---

## Testing

### Automated Testing

```javascript
// Using jest-axe
import { axe, toHaveNoViolations } from 'jest-axe';

expect.extend(toHaveNoViolations);

it('should have no accessibility violations', async () => {
  const { container } = render(<MyComponent />);
  const results = await axe(container);
  expect(results).toHaveNoViolations();
});
```

### Manual Testing Checklist

- [ ] Navigate entire page with keyboard only
- [ ] Test with screen reader (VoiceOver, NVDA)
- [ ] Check color contrast
- [ ] Zoom to 200% - still usable?
- [ ] Disable CSS - still understandable?
- [ ] Check all images have alt text
- [ ] Verify form labels and errors
- [ ] Test focus visibility
- [ ] Check heading structure

### Screen Reader Testing

| OS | Screen Reader | Browser |
|----|---------------|---------|
| macOS | VoiceOver | Safari |
| Windows | NVDA | Firefox |
| Windows | JAWS | Chrome |
| Mobile | TalkBack | Chrome |
| iOS | VoiceOver | Safari |

---

## Common Patterns

### Modal Dialog

```html
<div 
  role="dialog" 
  aria-modal="true" 
  aria-labelledby="dialog-title"
  aria-describedby="dialog-desc"
>
  <h2 id="dialog-title">Confirm Action</h2>
  <p id="dialog-desc">Are you sure you want to proceed?</p>
  
  <button>Cancel</button>
  <button>Confirm</button>
</div>
```

Focus management:
1. Move focus to modal on open
2. Trap focus inside modal
3. Return focus to trigger on close

### Tabs

```html
<div role="tablist" aria-label="Settings">
  <button role="tab" aria-selected="true" aria-controls="panel-1" id="tab-1">
    General
  </button>
  <button role="tab" aria-selected="false" aria-controls="panel-2" id="tab-2">
    Security
  </button>
</div>

<div role="tabpanel" id="panel-1" aria-labelledby="tab-1">
  General settings content
</div>
<div role="tabpanel" id="panel-2" aria-labelledby="tab-2" hidden>
  Security settings content
</div>
```

---

## References

- `references/wcag-checklist.md` - Full WCAG 2.1 checklist
- `references/aria-patterns.md` - Common ARIA patterns
- `references/testing-tools.md` - Testing tool setup

Related Skills

webhook-integration-patterns

from organvm-iv-taxis/a-i--skills

Designs reliable webhook systems with proper delivery guarantees, retry logic, signature verification, and idempotent processing for event-driven integrations.

vector-search-patterns

from organvm-iv-taxis/a-i--skills

Implement vector similarity search with embedding generation, index selection, and hybrid retrieval strategies. Covers ChromaDB, pgvector, FAISS, and RAG pipeline design. Triggers on vector search, embeddings, semantic search, or RAG architecture requests.

testing-patterns

from organvm-iv-taxis/a-i--skills

Write effective tests across the stack—unit, integration, E2E, and visual regression. Covers testing philosophy, framework selection, mocking strategies, and CI integration. Triggers on testing, test coverage, TDD, or quality assurance requests.

session-lifecycle-patterns

from organvm-iv-taxis/a-i--skills

Manage AI agent session lifecycles with structured phases (FRAME, SHAPE, BUILD, PROVE), context preservation across sessions, handoff protocols, and session metadata tracking. Triggers on session management, agent lifecycle, or multi-session workflow requests.

responsive-design-patterns

from organvm-iv-taxis/a-i--skills

Mobile-first responsive design patterns with breakpoints, fluid layouts, and adaptive components

resilience-patterns

from organvm-iv-taxis/a-i--skills

Build fault-tolerant systems with circuit breakers, retries with backoff, bulkheads, timeouts, and graceful degradation. Covers distributed system failure modes and recovery strategies. Triggers on reliability engineering, fault tolerance, or distributed system resilience requests.

redis-patterns

from organvm-iv-taxis/a-i--skills

Use Redis effectively for caching, pub/sub messaging, rate limiting, distributed locks, and session storage. Covers data structure selection, expiration strategies, and cluster patterns. Triggers on Redis usage, caching architecture, or pub/sub messaging requests.

realtime-websocket-patterns

from organvm-iv-taxis/a-i--skills

Implement real-time features with WebSockets, Server-Sent Events, and long polling. Covers connection management, room-based messaging, presence tracking, and scaling strategies. Triggers on WebSocket implementation, real-time communication, or live update feature requests.

react-three-fiber-patterns

from organvm-iv-taxis/a-i--skills

Build interactive 3D experiences in React using react-three-fiber (R3F), drei helpers, and shader integration. Covers scene composition, performance optimization, and animation patterns. Triggers on R3F development, React + Three.js, or declarative 3D scene requests.

python-packaging-patterns

from organvm-iv-taxis/a-i--skills

Structure Python projects for distribution with pyproject.toml, src layouts, dependency management, and publishing workflows. Covers packaging tools (hatch, setuptools, flit, poetry), versioning strategies, and editable installs. Triggers on Python project setup, packaging configuration, or dependency management requests.

prompt-engineering-patterns

from organvm-iv-taxis/a-i--skills

Design effective prompts for LLM agents with structured input/output formats, chain-of-thought reasoning, few-shot examples, and system prompt architecture. Covers Claude-specific patterns and multi-turn conversation design. Triggers on prompt design, LLM interaction patterns, or system prompt architecture requests.

postgres-advanced-patterns

from organvm-iv-taxis/a-i--skills

Advanced PostgreSQL patterns for performance optimization, complex queries, indexing strategies, and database design