web-guidelines

Instruction file imported from preetsuthar17/shadcn-marble-cms-blog-template (.cursor/rules/web-guidelines.mdc). Copyright stays with the author.

Concise rules for building accessible, fast, delightful UIs Use MUST/SHOULD/NEVER to guide decisions

Interactions

• Keyboard
  • MUST: Full keyboard support per WAI-ARIA APG
  • MUST: Visible focus rings (:focus-visible; group with :focus-within)
  • MUST: Manage focus (trap, move, and return) per APG patterns
• Targets & input
  • MUST: Hit target ≥24px (mobile ≥44px) If visual <24px, expand hit area
  • MUST: Mobile <input> font-size ≥16px or set:

    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, viewport-fit=cover">

  • NEVER: Disable browser zoom
  • MUST: touch-action: manipulation to prevent double-tap zoom; set -webkit-tap-highlight-color to match design
• Inputs & forms (behavior)
  • MUST: Hydration-safe inputs (no lost focus/value)
  • NEVER: Block paste in <input>/<textarea>
  • MUST: Loading buttons show spinner and keep original label
  • MUST: Enter submits focused text input In <textarea>, ⌘/Ctrl+Enter submits; Enter adds newline
  • MUST: Keep submit enabled until request starts; then disable, show spinner, use idempotency key
  • MUST: Don’t block typing; accept free text and validate after
  • MUST: Allow submitting incomplete forms to surface validation
  • MUST: Errors inline next to fields; on submit, focus first error
  • MUST: autocomplete + meaningful name; correct type and inputmode
  • SHOULD: Disable spellcheck for emails/codes/usernames
  • SHOULD: Placeholders end with ellipsis and show example pattern (eg, +1 (123) 456-7890, sk-012345…)
  • MUST: Warn on unsaved changes before navigation
  • MUST: Compatible with password managers & 2FA; allow pasting one-time codes
  • MUST: Trim values to handle text expansion trailing spaces
  • MUST: No dead zones on checkboxes/radios; label+control share one generous hit target
• State & navigation
  • MUST: URL reflects state (deep-link filters/tabs/pagination/expanded panels) Prefer libs like nuqs
  • MUST: Back/Forward restores scroll
  • MUST: Links are links—use <a>/<Link> for navigation (support Cmd/Ctrl/middle-click)
• Feedback
  • SHOULD: Optimistic UI; reconcile on response; on failure show error and rollback or offer Undo
  • MUST: Confirm destructive actions or provide Undo window
  • MUST: Use polite aria-live for toasts/inline validation
  • SHOULD: Ellipsis (…) for options that open follow-ups (eg, "Rename…") and loading states (eg, "Loading…", "Saving…", "Generating…")
• Touch/drag/scroll
  • MUST: Design forgiving interactions (generous targets, clear affordances; avoid finickiness)
  • MUST: Delay first tooltip in a group; subsequent peers no delay
  • MUST: Intentional overscroll-behavior: contain in modals/drawers
  • MUST: During drag, disable text selection and set inert on dragged element/containers
  • MUST: No “dead-looking” interactive zones—if it looks clickable, it is
• Autofocus
  • SHOULD: Autofocus on desktop when there’s a single primary input; rarely on mobile (to avoid layout shift)

Animation

• MUST: Honor prefers-reduced-motion (provide reduced variant)
• SHOULD: Prefer CSS > Web Animations API > JS libraries
• MUST: Animate compositor-friendly props (transform, opacity); avoid layout/repaint props (top/left/width/height)
• SHOULD: Animate only to clarify cause/effect or add deliberate delight
• SHOULD: Choose easing to match the change (size/distance/trigger)
• MUST: Animations are interruptible and input-driven (avoid autoplay)
• MUST: Correct transform-origin (motion starts where it “physically” should)

Layout

• SHOULD: Optical alignment; adjust by ±1px when perception beats geometry
• MUST: Deliberate alignment to grid/baseline/edges/optical centers—no accidental placement
• SHOULD: Balance icon/text lockups (stroke/weight/size/spacing/color)
• MUST: Verify mobile, laptop, ultra-wide (simulate ultra-wide at 50% zoom)
• MUST: Respect safe areas (use env(safe-area-inset-*))
• MUST: Avoid unwanted scrollbars; fix overflows

Content & Accessibility

• SHOULD: Inline help first; tooltips last resort
• MUST: Skeletons mirror final content to avoid layout shift
• MUST: <title> matches current context
• MUST: No dead ends; always offer next step/recovery
• MUST: Design empty/sparse/dense/error states
• SHOULD: Curly quotes (“ ”); avoid widows/orphans
• MUST: Tabular numbers for comparisons (font-variant-numeric: tabular-nums or a mono like Geist Mono)
• MUST: Redundant status cues (not color-only); icons have text labels
• MUST: Don’t ship the schema—visuals may omit labels but accessible names still exist
• MUST: Use the ellipsis character … (not ``)
• MUST: scroll-margin-top on headings for anchored links; include a “Skip to content” link; hierarchical <h1–h6>
• MUST: Resilient to user-generated content (short/avg/very long)
• MUST: Locale-aware dates/times/numbers/currency
• MUST: Accurate names (aria-label), decorative elements aria-hidden, verify in the Accessibility Tree
• MUST: Icon-only buttons have descriptive aria-label
• MUST: Prefer native semantics (button, a, label, table) before ARIA
• SHOULD: Right-clicking the nav logo surfaces brand assets
• MUST: Use non-breaking spaces to glue terms: 10 MB, ⌘ + K, Vercel SDK

Performance

• SHOULD: Test iOS Low Power Mode and macOS Safari
• MUST: Measure reliably (disable extensions that skew runtime)
• MUST: Track and minimize re-renders (React DevTools/React Scan)
• MUST: Profile with CPU/network throttling
• MUST: Batch layout reads/writes; avoid unnecessary reflows/repaints
• MUST: Mutations (POST/PATCH/DELETE) target <500 ms
• SHOULD: Prefer uncontrolled inputs; make controlled loops cheap (keystroke cost)
• MUST: Virtualize large lists (eg, virtua)
• MUST: Preload only above-the-fold images; lazy-load the rest
• MUST: Prevent CLS from images (explicit dimensions or reserved space)

Design

• SHOULD: Layered shadows (ambient + direct)
• SHOULD: Crisp edges via semi-transparent borders + shadows
• SHOULD: Nested radii: child ≤ parent; concentric
• SHOULD: Hue consistency: tint borders/shadows/text toward bg hue
• MUST: Accessible charts (color-blind-friendly palettes)
• MUST: Meet contrast—prefer APCA over WCAG 2
• MUST: Increase contrast on :hover/:active/:focus
• SHOULD: Match browser UI to bg
• SHOULD: Avoid gradient banding (use masks when needed)
• MUST: Use size- instead of w- h- (e.g., size-5 instead of w-5 h-5)
• MUST: Never use space-x or space-y. Use Flexbox and gaps.
• MUST: Never use hardcoded spaces like mb mt mr ml pb pt pr pl. Use Flexbox and gaps.