accessibility-design

name	accessibility-design
description	WCAG 2.1 AA compliance patterns, screen reader compatibility, keyboard navigation, and ARIA best practices. Use when implementing accessible interfaces, reviewing UI components, or auditing accessibility compliance. Covers semantic HTML, focus management, color contrast, and assistive technology testing.
license	MIT
compatibility	opencode
metadata	{"category":"design","version":"1.0"}

Accessibility Design

Roleplay as an accessibility specialist providing comprehensive guidance for implementing WCAG 2.1 AA compliance across digital products. Establishes patterns for semantic markup, assistive technology compatibility, and inclusive interaction design.

AccessibilityDesign { Activation { Implementing accessible user interfaces Reviewing UI components for accessibility compliance Auditing WCAG 2.1 AA compliance Designing keyboard navigation patterns Implementing ARIA for custom widgets Testing with screen readers and assistive technologies Ensuring color contrast and visual accessibility }

Constraints { 1. Semantic HTML first - ARIA should enhance, never replace proper markup 2. Use native HTML elements whenever possible 3. Never remove focus indicators entirely 4. Never rely on color alone to convey information 5. All functionality must be keyboard accessible 6. Maintain logical heading order without skipping levels }

POURFramework { Description: "All accessibility work follows the four POUR principles"

Perceivable {
  Provide text alternatives for non-text content
  Create content adaptable to different presentations
  Make content distinguishable (color, contrast, audio control)
}

Operable {
  Make all functionality keyboard accessible
  Provide sufficient time to read and use content
  Avoid content that causes seizures or physical reactions
  Help users navigate, find content, and determine location
}

Understandable {
  Make text readable and understandable
  Make pages appear and operate predictably
  Help users avoid and correct mistakes
}

Robust {
  Maximize compatibility with current and future assistive technologies
  Use valid, semantic markup
  Ensure programmatic access to all functionality
}

}

SemanticHTMLFirst { Correct { html <button type="submit">Submit Form</button> }

Incorrect {
  ```html
  <div role="button" tabindex="0" onclick="submit()">Submit Form</div>
  ```
}

NativeElements {
  `<button>` for actions
  `<a href>` for navigation
  `<input>`, `<select>`, `<textarea>` for form controls
  `<nav>`, `<main>`, `<aside>`, `<header>`, `<footer>` for landmarks
  `<h1>` through `<h6>` for heading hierarchy
}

}

ProgressiveEnhancement { 1. Semantic HTML provides baseline accessibility 2. CSS enhances presentation without breaking structure 3. JavaScript adds interactivity while maintaining keyboard access 4. ARIA fills gaps for complex widgets not covered by HTML }

ImplementationPatterns { DocumentStructure { ```html Descriptive Page Title - Site Name Skip to main content

    <header role="banner">
      <nav aria-label="Main navigation">
        <!-- Navigation content -->
      </nav>
    </header>

    <main id="main-content" role="main">
      <h1>Page Heading</h1>
      <!-- Page content -->
    </main>

    <footer role="contentinfo">
      <!-- Footer content -->
    </footer>
  </body>
  </html>
  ```
}

HeadingHierarchy {
  ```html
  <h1>Main Page Title</h1>
    <h2>Section Title</h2>
      <h3>Subsection Title</h3>
      <h3>Another Subsection</h3>
    <h2>Another Section</h2>
      <h3>Subsection</h3>
        <h4>Sub-subsection</h4>
  ```
}

SkipLinks {
  ```css
  .skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    padding: 8px 16px;
    background: #000;
    color: #fff;
    z-index: 100;
  }

  .skip-link:focus {
    top: 0;
  }
  ```
}

}

FocusManagement { VisibleFocusIndicators { ```css :focus { outline: 2px solid #005fcc; outline-offset: 2px; }

  /* Enhanced focus for better visibility */
  :focus-visible {
    outline: 3px solid #005fcc;
    outline-offset: 3px;
    box-shadow: 0 0 0 6px rgba(0, 95, 204, 0.25);
  }

  /* Never remove focus indicators entirely */
  :focus:not(:focus-visible) {
    outline: 2px solid transparent;
    box-shadow: 0 0 0 2px #005fcc;
  }
  ```
}

FocusTrappingForModals {
  ```javascript
  function trapFocus(element) {
    const focusableElements = element.querySelectorAll(
      'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
    );
    const firstFocusable = focusableElements[0];
    const lastFocusable = focusableElements[focusableElements.length - 1];

    element.addEventListener('keydown', (e) => {
      if (e.key !== 'Tab') return;

      if (e.shiftKey) {
        if (document.activeElement === firstFocusable) {
          lastFocusable.focus();
          e.preventDefault();
        }
      } else {
        if (document.activeElement === lastFocusable) {
          firstFocusable.focus();
          e.preventDefault();
        }
      }
    });
  }
  ```
}

}

KeyboardNavigation { StandardPatterns { | Key | Action | |-----|--------| | Tab | Move focus to next focusable element | | Shift+Tab | Move focus to previous focusable element | | Enter/Space | Activate buttons and links | | Arrow keys | Navigate within components (menus, tabs, radio groups) | | Escape | Close modals, menus, dropdowns | | Home/End | Move to first/last item in lists | }

TabOrder {
  ```html
  <!-- Correct: Tab order matches visual order -->
  <form>
    <label for="name">Name</label>
    <input id="name" type="text">

    <label for="email">Email</label>
    <input id="email" type="email">

    <button type="submit">Submit</button>
  </form>
  ```

  Rules {
    Never use positive `tabindex` values
    Use `tabindex="0"` to make non-interactive elements focusable
    Use `tabindex="-1"` to make elements programmatically focusable but not in tab order
  }
}

}

ARIAPatterns { WhenToUseARIA { Custom widgets: Tabs, accordions, carousels, tree views Dynamic content: Live regions for updates Relationships: Connecting labels to complex controls States: Expanded/collapsed, selected, pressed }

ARIARoles {
  ```html
  <!-- Tab pattern -->
  <div role="tablist" aria-label="Settings tabs">
    <button role="tab" aria-selected="true" aria-controls="panel1" id="tab1">
      General
    </button>
    <button role="tab" aria-selected="false" aria-controls="panel2" id="tab2">
      Security
    </button>
  </div>
  <div role="tabpanel" id="panel1" aria-labelledby="tab1">
    <!-- Panel content -->
  </div>
  <div role="tabpanel" id="panel2" aria-labelledby="tab2" hidden>
    <!-- Panel content -->
  </div>
  ```
}

ARIAStatesAndProperties {
  | Attribute | Purpose | Example |
  |-----------|---------|---------|
  | `aria-expanded` | Indicates expandable element state | `aria-expanded="false"` |
  | `aria-selected` | Indicates selection state | `aria-selected="true"` |
  | `aria-pressed` | Indicates toggle button state | `aria-pressed="mixed"` |
  | `aria-hidden` | Hides content from assistive tech | `aria-hidden="true"` |
  | `aria-live` | Announces dynamic content | `aria-live="polite"` |
  | `aria-describedby` | References descriptive content | `aria-describedby="hint"` |
  | `aria-labelledby` | References labeling content | `aria-labelledby="heading"` |
}

LiveRegions {
  ```html
  <!-- Polite: Announces when user is idle -->
  <div aria-live="polite" aria-atomic="true">
    Form saved successfully
  </div>

  <!-- Assertive: Interrupts immediately (use sparingly) -->
  <div aria-live="assertive" role="alert">
    Error: Please correct the highlighted fields
  </div>

  <!-- Status messages -->
  <div role="status">
    Loading... 50% complete
  </div>
  ```
}

}

FormAccessibility { LabelsAndInstructions { ```html Username Must be 3-20 characters

  <!-- Grouped controls with fieldset -->
  <fieldset>
    <legend>Shipping Address</legend>
    <label for="street">Street</label>
    <input type="text" id="street">
    <!-- More fields -->
  </fieldset>
  ```
}

ErrorHandling {
  ```html
  <label for="email">Email</label>
  <input type="email" id="email"
         aria-invalid="true"
         aria-describedby="email-error">
  <span id="email-error" role="alert">
    Please enter a valid email address (example: [e-mail])
  </span>
  ```

  Requirements {
    Identify the field in error
    Describe what went wrong
    Provide guidance for correction
    Use `aria-invalid` on the field
    Announce errors via live region or `role="alert"`
  }
}

RequiredFields {
  ```html
  <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">
  ```
}

}

ImagesAndMedia { AlternativeText { ```html

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

  <!-- Complex image with extended description -->
  <figure>
    <img src="flowchart.png" alt="User registration process"
         aria-describedby="flowchart-desc">
    <figcaption id="flowchart-desc">
      The registration process begins with email verification,
      followed by profile creation, and ends with account activation.
    </figcaption>
  </figure>
  ```
}

VideoAndAudio {
  ```html
  <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>
  ```
}

}

ColorAndContrast { MinimumContrastRatios { | Content Type | Minimum Ratio (AA) | Enhanced Ratio (AAA) | |--------------|-------------------|---------------------| | Normal text (< 18pt) | 4.5:1 | 7:1 | | Large text (>= 18pt or 14pt bold) | 3:1 | 4.5:1 | | UI components and graphics | 3:1 | N/A | }

NeverRelyOnColorAlone {
  ```html
  <!-- Bad: Color only indicates error -->
  <input style="border-color: red">

  <!-- Good: Color plus icon and text -->
  <input aria-invalid="true" aria-describedby="error">
  <span id="error">
    <svg aria-hidden="true"><!-- Error icon --></svg>
    Invalid email format
  </span>
  ```
}

}

MotionAndAnimation { RespectUserPreferences { css /* Reduce motion for users who prefer it */ @media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; } } }

AutoPlayingContent {
  Avoid auto-playing video or audio
  Provide controls to pause, stop, or hide moving content
  Limit animations to under 5 seconds or provide stop mechanism
}

}

TestingMethodology { AutomatedTesting { Tools { axe DevTools: Browser extension for page analysis WAVE: Web accessibility evaluation tool Lighthouse: Chrome DevTools accessibility audit pa11y: Command-line accessibility testing }

  Note: "Automated testing catches approximately 30-40% of issues"
}

KeyboardTesting {
  1. Disconnect or disable mouse
  2. Navigate entire page using Tab/Shift+Tab
  3. Verify all interactive elements are reachable
  4. Verify focus indicators are visible
  5. Test all keyboard shortcuts
  6. Escape from all modals and menus
}

ScreenReaderTesting {
  Platforms {
    | Platform | Screen Reader | Browser |
    |----------|---------------|---------|
    | Windows | NVDA (free) | Firefox, Chrome |
    | Windows | JAWS | Chrome, Edge |
    | macOS | VoiceOver | Safari |
    | iOS | VoiceOver | Safari |
    | Android | TalkBack | Chrome |
  }

  Checklist {
    All images have appropriate alt text
    Headings convey page structure
    Links and buttons have descriptive names
    Form fields have labels
    Error messages are announced
    Dynamic content updates are announced
    Tables have proper headers
    Custom widgets announce state changes
  }
}

VisualTesting {
  Zoom to 200% and verify no horizontal scrolling
  Test with high contrast mode enabled
  Disable images and verify content is still understandable
  Test with browser text size increased
}

}

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

  Requirements {
    Focus moves to dialog when opened
    Focus is trapped within dialog
    Escape key closes dialog
    Focus returns to trigger element on close
  }
}

Accordion {
  ```html
  <div class="accordion">
    <h3>
      <button aria-expanded="true" aria-controls="section1">
        Section 1
      </button>
    </h3>
    <div id="section1" role="region" aria-labelledby="section1-heading">
      <!-- Content -->
    </div>
  </div>
  ```
}

NavigationMenu {
  ```html
  <nav aria-label="Main">
    <ul>
      <li><a href="/" aria-current="page">Home</a></li>
      <li>
        <button aria-expanded="false" aria-haspopup="true">
          Products
        </button>
        <ul>
          <li><a href="/products/a">Product A</a></li>
          <li><a href="/products/b">Product B</a></li>
        </ul>
      </li>
    </ul>
  </nav>
  ```
}

DataTable {
  ```html
  <table>
    <caption>Q3 Sales by Region</caption>
    <thead>
      <tr>
        <th scope="col">Region</th>
        <th scope="col">Units Sold</th>
        <th scope="col">Revenue</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <th scope="row">North</th>
        <td>1,234</td>
        <td>$45,678</td>
      </tr>
    </tbody>
  </table>
  ```
}

} }

Resources

• WCAG 2.1 Guidelines
• WAI-ARIA Authoring Practices
• Inclusive Components
• A11y Project Checklist