emilkowal-animations

SKILL.md

Emil Kowalski Animation Best Practices

Comprehensive animation guide for web interfaces based on Emil Kowalski's teachings, open-source libraries (Sonner, Vaul), and his animations.dev course. Contains 43 rules across 7 categories, prioritized by impact.

When to Apply

Reference these guidelines when:

Adding animations to React components

Choosing easing curves or timing values

Implementing gesture-based interactions (swipe, drag)

Building toast notifications or drawer components

Optimizing animation performance

Ensuring animation accessibility

Rule Categories by Priority

Priority
Category
Impact
Prefix

1
Easing Selection
CRITICAL
ease-

2
Timing & Duration
CRITICAL
timing-

3
Property Selection
HIGH
props-

4
Transform Techniques
HIGH
transform-

5
Interaction Patterns
MEDIUM-HIGH
interact-

6
Strategic Animation
MEDIUM
strategy-

7
Accessibility & Polish
MEDIUM
polish-

Quick Reference

1. Easing Selection (CRITICAL)

ease-out-default - Use ease-out as your default easing

ease-custom-curves - Use custom cubic-bezier over built-in CSS

ease-in-out-onscreen - Use ease-in-out for on-screen movement

ease-spring-natural - Use spring animations for natural motion

ease-ios-drawer - Use iOS-style easing for drawer components

ease-context-matters - Match easing to animation context

2. Timing & Duration (CRITICAL)

timing-300ms-max - Keep UI animations under 300ms

timing-faster-better - Faster animations improve perceived performance

timing-asymmetric - Use asymmetric timing for press and release

timing-tooltip-delay - Delay initial tooltips, instant subsequent ones

timing-drawer-500ms - Use 500ms duration for drawer animations

3. Property Selection (HIGH)

props-transform-opacity - Animate only transform and opacity

props-hardware-accelerated - Use hardware-accelerated animations when main thread is busy

props-will-change - Use will-change to prevent 1px shift

props-avoid-css-variables - Avoid CSS variables for drag animations

props-clip-path-performant - Use clip-path for layout-free reveals

4. Transform Techniques (HIGH)

transform-scale-097 - Scale buttons to 0.97 on press

transform-never-scale-zero - Never animate from scale(0)

transform-percentage-translate - Use percentage values for translateY

transform-origin-aware - Make animations origin-aware

transform-scale-children - Scale transforms affect children

transform-3d-preserve - Use preserve-3d for 3D transform effects

5. Interaction Patterns (MEDIUM-HIGH)

interact-interruptible - Make animations interruptible

interact-momentum-dismiss - Use momentum-based dismissal

interact-damping - Damp drag at boundaries

interact-scroll-drag-conflict - Resolve scroll and drag conflicts

interact-snap-points - Implement velocity-aware snap points

interact-friction-upward - Allow upward drag with friction

interact-pointer-capture - Use pointer capture for drag operations

6. Strategic Animation (MEDIUM)

strategy-keyboard-no-animate - Never animate keyboard-initiated actions

strategy-frequency-matters - Consider interaction frequency before animating

strategy-purpose-required - Every animation must have a purpose

strategy-feedback-immediate - Provide immediate feedback on all actions

strategy-marketing-exception - Marketing sites are the exception

7. Accessibility & Polish (MEDIUM)

polish-reduced-motion - Respect prefers-reduced-motion

polish-opacity-fallback - Use opacity as reduced motion fallback

polish-framer-hook - Use useReducedMotion hook in Framer Motion

polish-dont-remove-all - Don't remove all animation for reduced motion

polish-blur-bridge - Use blur to bridge animation states

polish-clip-path-tabs - Use clip-path for tab transitions

polish-toast-stacking - Implement toast stacking with scale and offset

polish-scroll-reveal - Trigger scroll animations at appropriate threshold

polish-hover-gap-fill - Fill gaps between hoverable elements

polish-stagger-children - Stagger child animations for orchestration

Key Values Reference

Value
Usage

cubic-bezier(0.32, 0.72, 0, 1)
iOS-style drawer/sheet animation

scale(0.97)
Button press feedback

scale(0.95)
Minimum enter scale (never scale(0))

200ms ease-out
Standard UI transition

300ms
Maximum duration for UI animations

500ms
Drawer animation duration

0.11 px/ms
Velocity threshold for momentum dismiss

100px
Scroll-reveal viewport threshold

14px
Toast stack offset

Reference Files

File
Description

references/_sections.md
Category definitions and ordering

assets/templates/_template.md
Template for new rules

metadata.json
Version and reference information