User Interface Wiki

Comprehensive UI/UX best practices guide for web interfaces. Contains 131 rules across 11 categories, prioritized by impact to guide automated code review and generation.

When to Apply

Reference these guidelines when:

Implementing or reviewing animations (CSS transitions, Motion/Framer Motion)
Choosing between springs, easing curves, or no animation
Working with AnimatePresence and exit animations
Writing CSS with pseudo-elements or View Transitions API
Adding audio feedback or procedural sound to UI
Building morphing icon components
Animating container width/height with dynamic content
Designing UI that respects cognitive psychology (Fitts's, Hick's, Miller's laws)
Implementing predictive prefetching for perceived performance
Setting up typography, OpenType features, or numeric formatting

Rule Categories by Priority


timing-
spring-
exit-
pseudo-
a11y-
context-
morphing-
container-
ux-
prefetch-
type-

Priority	Category	Impact	Prefixes
1	Animation Principles	CRITICAL	`timing-` , `physics-` , `staging-`
2	Timing Functions	HIGH	`spring-` , `easing-` , `duration-` , `none-`
3	Exit Animations	HIGH	`exit-` , `presence-` , `mode-` , `nested-`
4	CSS Pseudo Elements	MEDIUM	`pseudo-` , `transition-` , `native-`
5	Audio Feedback	MEDIUM	`a11y-` , `appropriate-` , `impl-` , `weight-`
6	Sound Synthesis	MEDIUM	`context-` , `envelope-` , `design-` , `param-`
7	Morphing Icons	LOW	`morphing-`
8	Container Animation	MEDIUM	`container-`
9	Laws of UX	HIGH	`ux-`
10	Predictive Prefetching	MEDIUM	`prefetch-`
11	Typography	MEDIUM	`type-`

Quick Reference

1. Animation Principles (CRITICAL)

```
timing-under-300ms
```
- User animations must complete within 300ms
```
timing-consistent
```
- Similar elements use identical timing values
```
timing-no-entrance-context-menu
```
- Context menus: no entrance animation, exit only
```
easing-natural-decay
```
- Use exponential ramps for natural decay, not linear
```
easing-no-linear-motion
```
- Linear easing only for progress indicators
```
physics-active-state
```
- Interactive elements need :active scale transform
```
physics-subtle-deformation
```
- Squash/stretch in 0.95-1.05 range
```
physics-spring-for-overshoot
```
- Springs for overshoot-and-settle, not easing
```
physics-no-excessive-stagger
```
- Stagger delays under 50ms per item
```
staging-one-focal-point
```
- One prominent animation at a time
```
staging-dim-background
```
- Dim modal/dialog backgrounds
```
staging-z-index-hierarchy
```
- Animated elements respect z-index layers

2. Timing Functions (HIGH)

```
spring-for-gestures
```
- Gesture-driven motion (drag, flick) must use springs
```
spring-for-interruptible
```
- Interruptible motion must use springs
```
spring-preserves-velocity
```
- Springs preserve input energy on release
```
spring-params-balanced
```
- Avoid excessive oscillation in spring params
```
easing-for-state-change
```
- System state changes use easing curves
```
easing-entrance-ease-out
```
- Entrances use ease-out
```
easing-exit-ease-in
```
- Exits use ease-in
```
easing-transition-ease-in-out
```
- View transitions use ease-in-out
```
easing-linear-only-progress
```
- Linear only for progress/time representation
```
duration-press-hover
```
- Press/hover: 120-180ms
```
duration-small-state
```
- Small state changes: 180-260ms
```
duration-max-300ms
```
- User-initiated max 300ms
```
duration-shorten-before-curve
```
- Fix slow feel with shorter duration, not curve
```
none-high-frequency
```
- No animation for high-frequency interactions
```
none-keyboard-navigation
```
- Keyboard navigation instant, no animation
```
none-context-menu-entrance
```
- Context menus: no entrance, exit only

3. Exit Animations (HIGH)

```
exit-requires-wrapper
```
- Conditional motion elements need AnimatePresence wrapper
```
exit-prop-required
```
- Elements in AnimatePresence need exit prop
```
exit-key-required
```
- Dynamic lists need unique keys, not index
```
exit-matches-initial
```
- Exit mirrors initial for symmetry
```
presence-hook-in-child
```
- useIsPresent in child, not parent
```
presence-safe-to-remove
```
- Call safeToRemove after async cleanup
```
presence-disable-interactions
```
- Disable interactions on exiting elements
```
mode-wait-doubles-duration
```
- Mode "wait" doubles duration; halve timing
```
mode-sync-layout-conflict
```
- Mode "sync" causes layout conflicts
```
mode-pop-layout-for-lists
```
- Use popLayout for list reordering
```
nested-propagate-required
```
- Nested AnimatePresence needs propagate prop
```
nested-consistent-timing
```
- Coordinate parent-child exit durations

4. CSS Pseudo Elements (MEDIUM)

```
pseudo-content-required
```
- ::before/::after need content property
```
pseudo-over-dom-node
```
- Pseudo-elements over extra DOM nodes for decoration
```
pseudo-position-relative-parent
```
- Parent needs position: relative
```
pseudo-z-index-layering
```
- Z-index for correct pseudo-element layering
```
pseudo-hit-target-expansion
```
- Negative inset for larger hit targets
```
transition-name-required
```
- View transitions need view-transition-name
```
transition-name-unique
```
- Each transition name unique during transition
```
transition-name-cleanup
```
- Remove transition name after completion
```
transition-over-js-library
```
- Prefer View Transitions API over JS libraries
```
transition-style-pseudo-elements
```
- Style ::view-transition-group for custom animations
```
native-backdrop-styling
```
- Use ::backdrop for dialog backgrounds
```
native-placeholder-styling
```
- Use ::placeholder for input styling
```
native-selection-styling
```
- Use ::selection for text selection styling

5. Audio Feedback (MEDIUM)

```
a11y-visual-equivalent
```
- Every sound must have a visual equivalent
```
a11y-toggle-setting
```
- Provide toggle to disable sounds
```
a11y-reduced-motion-check
```
- Respect prefers-reduced-motion for sound
```
a11y-volume-control
```
- Allow independent volume adjustment
```
appropriate-no-high-frequency
```
- No sound on typing or keyboard nav
```
appropriate-confirmations-only
```
- Sound for payments, uploads, submissions
```
appropriate-errors-warnings
```
- Sound for errors that can't be overlooked
```
appropriate-no-decorative
```
- No sound on hover or decorative moments
```
appropriate-no-punishing
```
- Inform, don't punish with harsh sounds
```
impl-preload-audio
```
- Preload audio files to avoid delay
```
impl-default-subtle
```
- Default volume subtle (0.3), not loud
```
impl-reset-current-time
```
- Reset currentTime before replay
```
weight-match-action
```
- Sound weight matches action importance
```
weight-duration-matches-action
```
- Sound duration matches action duration

6. Sound Synthesis (MEDIUM)

```
context-reuse-single
```
- Reuse single AudioContext, don't create per sound
```
context-resume-suspended
```
- Resume suspended AudioContext before playing
```
context-cleanup-nodes
```
- Disconnect audio nodes after playback
```
envelope-exponential-decay
```
- Exponential ramps for natural decay
```
envelope-no-zero-target
```
- Exponential ramps target 0.001, not 0
```
envelope-set-initial-value
```
- Set initial value before ramping
```
design-noise-for-percussion
```
- Filtered noise for clicks/taps
```
design-oscillator-for-tonal
```
- Oscillators with pitch sweep for tonal sounds
```
design-filter-for-character
```
- Bandpass filter to shape percussive sounds
```
param-click-duration
```
- Click sounds: 5-15ms duration
```
param-filter-frequency-range
```
- Click filter: 3000-6000Hz
```
param-reasonable-gain
```
- Gain under 1.0 to prevent clipping
```
param-q-value-range
```
- Filter Q: 2-5 for focused but natural

7. Morphing Icons (LOW)

```
morphing-three-lines
```
- Every icon uses exactly 3 SVG lines
```
morphing-use-collapsed
```
- Unused lines use collapsed constant
```
morphing-consistent-viewbox
```
- All icons share same viewBox (14x14)
```
morphing-group-variants
```
- Rotational variants share group and base lines
```
morphing-spring-rotation
```
- Spring physics for grouped icon rotation
```
morphing-reduced-motion
```
- Respect prefers-reduced-motion
```
morphing-jump-non-grouped
```
- Instant rotation jump between non-grouped icons
```
morphing-strokelinecap-round
```
- Round stroke line caps
```
morphing-aria-hidden
```
- Icon SVGs are aria-hidden

8. Container Animation (MEDIUM)

```
container-two-div-pattern
```
- Outer animated div, inner measured div; never same element
```
container-guard-initial-zero
```
- Guard bounds === 0 on initial render, fall back to "auto"
```
container-use-resize-observer
```
- Use ResizeObserver for measurement, not getBoundingClientRect
```
container-overflow-hidden
```
- Set overflow: hidden on animated container during transitions
```
container-no-excessive-use
```
- Use sparingly: buttons, accordions, interactive elements
```
container-callback-ref
```
- Use callback ref (not useRef) for measurement hooks

9. Laws of UX (HIGH)

```
ux-fitts-target-size
```
- Size interactive targets for easy clicking (min 32px)
```
ux-fitts-hit-area
```
- Expand hit areas with invisible padding or pseudo-elements
```
ux-hicks-minimize-choices
```
- Minimize choices to reduce decision time
```
ux-millers-chunking
```
- Chunk data into groups of 5-9 for scannability
```
ux-doherty-under-400ms
```
- Respond within 400ms to feel instant
```
ux-doherty-perceived-speed
```
- Fake speed with skeletons, optimistic UI, progress indicators
```
ux-postels-accept-messy-input
```
- Accept messy input, output clean data
```
ux-progressive-disclosure
```
- Show what matters now, reveal complexity later
```
ux-jakobs-familiar-patterns
```
- Use familiar UI patterns users know from other sites
```
ux-aesthetic-usability
```
- Visual polish increases perceived usability
```
ux-proximity-grouping
```
- Group related elements spatially with tighter spacing
```
ux-similarity-consistency
```
- Similar elements should look alike
```
ux-common-region-boundaries
```
- Use boundaries to group related content
```
ux-von-restorff-emphasis
```
- Make important elements visually distinct
```
ux-serial-position
```
- Place key items first or last in sequences
```
ux-peak-end-finish-strong
```
- End experiences with clear success states
```
ux-teslers-complexity
```
- Move complexity to the system, not the user
```
ux-goal-gradient-progress
```
- Show progress toward completion
```
ux-zeigarnik-show-incomplete
```
- Show incomplete state to drive completion
```
ux-pragnanz-simplify
```
- Simplify complex visuals into clear forms

10. Predictive Prefetching (MEDIUM)

```
prefetch-trajectory-over-hover
```
- Trajectory prediction over hover; reclaims 100-200ms
```
prefetch-not-everything
```
- Prefetch by intent, not viewport; avoid wasted bandwidth
```
prefetch-hit-slop
```
- Use hitSlop to trigger predictions earlier
```
prefetch-touch-fallback
```
- Fall back gracefully on touch devices (no cursor)
```
prefetch-keyboard-tab
```
- Prefetch on keyboard navigation when focus approaches
```
prefetch-use-selectively
```
- Use predictive prefetching where latency is noticeable

11. Typography (MEDIUM)

```
type-tabular-nums-for-data
```
- Tabular numbers for columns, dashboards, pricing
```
type-oldstyle-nums-for-prose
```
- Oldstyle numbers blend into body text
```
type-slashed-zero
```
- Slashed zero in code-adjacent UIs
```
type-opentype-contextual-alternates
```
- Keep calt enabled for contextual glyph adjustment
```
type-disambiguation-stylistic-set
```
- Enable ss02 to distinguish I/l/1 and 0/O
```
type-optical-sizing-auto
```
- Leave font-optical-sizing auto for size-adaptive glyphs
```
type-antialiased-on-retina
```
- Antialiased font smoothing on retina displays
```
type-text-wrap-balance-headings
```
- text-wrap: balance on headings for even lines
```
type-underline-offset
```
- Offset underlines below descenders
```
type-no-font-synthesis
```
- Disable font-synthesis to prevent faux bold/italic

How to Use

Read individual rule files for detailed explanations and code examples:

rules/timing-under-300ms.md
rules/spring-for-gestures.md
rules/ux-doherty-under-400ms.md
rules/type-tabular-nums-for-data.md

Each rule file contains:

Brief explanation of why it matters
Incorrect code example with explanation
Correct code example with explanation

Full Compiled Document

For the complete guide with all rules expanded:

AGENTS.md

userinterface-wiki

NPX Install

Tags

SKILL.md Content