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name: web-design-guidelines description: Web Interface Guidelines for reviewing UI code compliance with modern design principles and accessibility standards.

Web Interface Guidelines

Review files for compliance with Web Interface Guidelines - a comprehensive set of rules for building modern, accessible, and performant web interfaces.

When to Apply

Use these guidelines when:

• Building new UI components
• Reviewing frontend code
• Ensuring accessibility compliance
• Optimizing user experience
• Establishing design system patterns

Core Principles

1. Semantic HTML

• Use appropriate HTML elements for their intended purpose
• Prefer <button> over <div onClick>
• Use heading hierarchy (h1 → h6) correctly
• Use <nav>, <main>, <aside>, <footer> for page structure
• Use <ul>/<ol> for lists, not divs with CSS

2. Accessibility (a11y)

• All interactive elements must be keyboard accessible
• Provide meaningful alt text for images
• Use aria-label when visual context is insufficient
• Ensure sufficient color contrast (WCAG AA: 4.5:1 for text)
• Don't rely on color alone to convey information
• Support reduced motion preferences
• Focus states must be visible

3. Responsive Design

• Mobile-first approach
• Use relative units (rem, em, %) over fixed (px)
• Test at multiple breakpoints
• Touch targets minimum 44x44px
• Content should be readable without horizontal scrolling

4. Performance

• Lazy load below-the-fold content
• Optimize images (WebP, proper sizing)
• Minimize layout shifts (CLS)
• Use CSS containment where appropriate
• Prefer CSS animations over JavaScript

5. Forms

• Always associate labels with inputs
• Provide clear error messages
• Use appropriate input types (email, tel, number)
• Support autofill with correct autocomplete attributes
• Show loading/success/error states

Output Format

When reviewing code, report findings as:

Copyfile:line - [severity] rule-name: description

Severities:

• [error] - Must fix, breaks functionality or accessibility
• [warning] - Should fix, impacts UX or performance
• [info] - Consider fixing, best practice improvement

Examples

Good Button Implementation

Copy<button
  type="button"
  onClick={handleClick}
  disabled={isLoading}
  aria-busy={isLoading}
  className="px-4 py-2 rounded-md bg-primary text-primary-foreground hover:bg-primary/90 focus-visible:outline-none focus-visible:ring-2"
>
  {isLoading ? <Spinner aria-hidden /> : null}
  {isLoading ? 'Saving...' : 'Save'}
</button>

Good Form Implementation

Copy<form onSubmit={handleSubmit}>
  <div className="space-y-4">
    <div>
      <label htmlFor="email" className="block text-sm font-medium">
        Email
      </label>
      <input
        id="email"
        type="email"
        name="email"
        autoComplete="email"
        required
        aria-describedby={error ? 'email-error' : undefined}
        className="mt-1 block w-full rounded-md border"
      />
      {error && (
        <p id="email-error" role="alert" className="mt-1 text-sm text-destructive">
          {error}
        </p>
      )}
    </div>
    <button type="submit">Submit</button>
  </div>
</form>

Good Image Implementation

Copy<Image
  src="/hero.webp"
  alt="Dashboard showing analytics overview with charts and metrics"
  width={1200}
  height={600}
  priority // Above the fold
  className="rounded-lg"
/>

Checklist

Before shipping UI code, verify:

• All interactive elements are keyboard accessible
• Forms have proper labels and error handling
• Images have meaningful alt text
• Color contrast meets WCAG AA
• Component works at mobile breakpoints
• Loading and error states are handled
• Focus states are visible
• No accessibility violations in DevTools audit

Attribution

Based on vercel-labs/agent-skills web-design-guidelines - 16K+ installs.