web-design-guidelines

name	web-design-guidelines
description	Review UI code for Web Interface Guidelines compliance. Use when asked to "review my UI", "check accessibility", "audit design", "review UX", "check my site against best practices", or "web interface guidelines".

Web Interface Guidelines

When to Load

• Trigger: UI audit, accessibility checks, responsive design review, UX best practices evaluation
• Skip: Backend-only work with no UI components

Self-contained guidelines for reviewing web interfaces. Apply these rules when auditing UI code.

Output Format

Report findings as: file:line — [RULE_ID] description

Example: src/Button.tsx:12 — [A11Y-01] Missing aria-label on icon button

1. Accessibility (A11Y)

A11Y-01: Semantic HTML

• Use <button> for actions, <a> for navigation, <input> for data entry
• Never use <div onClick> or <span onClick> for interactive elements
• Use <nav>, <main>, <aside>, <header>, <footer> for landmarks

A11Y-02: ARIA Labels

• All interactive elements need accessible names
• Icon-only buttons MUST have aria-label
• Form inputs MUST have associated <label> or aria-label
• Images need alt text (decorative images: alt="")

A11Y-03: Keyboard Navigation

• All interactive elements must be reachable via Tab
• Custom components need proper role, tabIndex, and key handlers
• Focus must be visible (never outline: none without replacement)
• Modal/dialog must trap focus and return focus on close

A11Y-04: Color & Contrast

• Text contrast ratio: 4.5:1 minimum (3:1 for large text)
• Never use color alone to convey meaning (add icons, text, patterns)
• Ensure UI is usable at 200% zoom

A11Y-05: Screen Readers

• Dynamic content changes need aria-live regions
• Loading states need aria-busy="true"
• Error messages linked to inputs via aria-describedby

2. Performance (PERF)

PERF-01: Image Optimization

• Use next/image or responsive images with srcset
• Specify width and height to prevent layout shift
• Lazy load below-fold images: loading="lazy"
• Use WebP/AVIF with fallback

PERF-02: Bundle Size

• No full library imports: import { Button } from 'lib' not import lib
• Tree-shake CSS: use CSS modules or Tailwind purge
• Lazy load routes and heavy components: React.lazy() or dynamic imports

PERF-03: Rendering

• Avoid layout thrashing: don't read then write DOM in loops
• Use will-change sparingly (only for known animations)
• Prefer CSS animations over JS animations
• Use transform and opacity for 60fps animations (compositor-only)

PERF-04: Core Web Vitals

• LCP < 2.5s: Optimize largest image/text, preload critical resources
• FID/INP < 200ms: No long tasks on main thread, defer non-critical JS
• CLS < 0.1: Set dimensions on images/embeds, no injected content above fold

3. Responsive Design (RD)

RD-01: Mobile First

• Base styles for mobile, then @media (min-width) for larger screens
• Touch targets minimum 44x44px
• No horizontal scroll on any viewport

RD-02: Fluid Layout

• Use rem/em for typography, not px
• Use clamp() for fluid typography: font-size: clamp(1rem, 2.5vw, 2rem)
• Flex/Grid over fixed widths
• Max content width: max-width: 65ch for readability

RD-03: Breakpoints

• Don't target devices, target content breakpoints
• Common: 640px (sm), 768px (md), 1024px (lg), 1280px (xl)
• Test at 320px, 375px, 768px, 1024px, 1440px, 1920px

4. Component Patterns (CP)

CP-01: Forms

• Show validation errors inline, next to the field
• Use type="email", type="tel", inputmode="numeric" for mobile keyboards
• Disable submit button during submission (prevent double-submit)
• Preserve form state on error (don't clear fields)

CP-02: Loading States

• Show skeleton screens over spinners for content areas
• Indicate progress for long operations (progress bar > spinner)
• Disable interactive elements during loading
• Set aria-busy="true" on loading containers

CP-03: Error States

• Always show actionable error messages ("Try again" button, not just "Error")
• Don't show technical errors to users (log internally, show friendly message)
• Error boundaries for React component trees
• Retry logic for network failures

CP-04: Empty States

• Never show blank pages — provide helpful empty states
• Include call-to-action: "No items yet. Create your first item."
• Use illustrations sparingly (they add bundle weight)

CP-05: Modals & Dialogs

• Use <dialog> element or proper role="dialog"
• Trap focus within modal
• Close on Escape key and backdrop click
• Return focus to trigger element on close
• Prevent body scroll while open

5. CSS Practices (CSS)

CSS-01: Specificity

• Prefer class selectors over ID or element selectors
• Avoid !important (use specificity or cascade layers)
• Use CSS custom properties for theming
• One direction for spacing: prefer margin-bottom over margin-top

CSS-02: Layout

• Use Flexbox for 1D layout, Grid for 2D layout
• Avoid position: absolute for layout (use for overlays only)
• Use gap over margins between flex/grid children
• Use min-height: 100dvh (not 100vh) for full-height layouts

CSS-03: Dark Mode

• Use prefers-color-scheme media query
• Define all colors as CSS custom properties
• Test both modes — check contrast in both
• Don't just invert colors — design intentionally for dark mode

6. Security (SEC)

SEC-01: Content Security

• Never use dangerouslySetInnerHTML without sanitization
• Sanitize user-generated content before rendering
• Use rel="noopener noreferrer" on external links with target="_blank"

SEC-02: Forms & Input

• CSRF protection on all forms
• Rate limit form submissions
• Validate on both client AND server

7. Internationalization (I18N)

I18N-01: Text

• Don't hardcode strings — use i18n library or constants
• Support RTL layouts: use logical properties (margin-inline-start over margin-left)
• Don't truncate text — designs must accommodate 40% text expansion
• Use lang attribute on <html> tag

Review Checklist

When auditing a file, check in this order (CRITICAL first):

1. CRITICAL: A11Y-01, A11Y-02, SEC-01 — Semantic HTML, ARIA, XSS prevention
2. HIGH: PERF-04, A11Y-03, CP-01 — Core Web Vitals, keyboard, forms
3. MEDIUM: RD-01, CSS-02, CP-02, CP-03 — Responsive, layout, loading/errors
4. LOW: CSS-03, I18N-01, CP-04 — Dark mode, i18n, empty states