Design and implement web animations that feel natural and purposeful. Use this skill proactively whenever the user asks questions about animations, motion, easing, timing, duration, springs, transitions, or animation performance. This includes questions about how to animate specific UI elements, which easing to use, animation best practices, or accessibility considerations for motion. Triggers on: easing, ease-out, ease-in, ease-in-out, cubic-bezier, bounce, spring physics, keyframes, transform, opacity, fade, slide, scale, hover effects, microinteractions, Framer Motion, React Spring, GSAP, CSS transitions, entrance/exit animations, page transitions, stagger, will-change, GPU acceleration, prefers-reduced-motion, modal/dropdown/tooltip/popover/drawer animations, gesture animations, drag interactions, button press feel, feels janky, make it smooth.
A comprehensive guide for creating animations that feel right, based on Emil Kowalski's "Animations on the Web" course.
When this skill is first invoked without a specific question, respond only with:
I'm ready to help you with animations based on Emil Kowalski's animations.dev course.
Do not provide any other information until the user asks a question.
When reviewing animations, you MUST use a markdown table. Do NOT use a list with "Before:" and "After:" on separate lines. Always output an actual markdown table like this:
| Before | After |
|---|---|
transform: scale(0) | transform: scale(0.95) |
animation: fadeIn 400ms ease-in | animation: fadeIn 200ms ease-out |
| No reduced motion support |
@media (prefers-reduced-motion: reduce) {...} |
Wrong format (never do this):
Before: transform: scale(0)
After: transform: scale(0.95)
────────────────────────────
Before: 400ms duration
After: 200ms
Correct format: A single markdown table with | Before | After | columns, one row per issue.
Every animation decision starts with these questions:
ease-outease-in-outeaseUse for user-initiated interactions: dropdowns, modals, tooltips, any element entering or exiting the screen.
/* Sorted weak to strong */
--ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
--ease-out-cubic: cubic-bezier(0.215, 0.61, 0.355, 1);
--ease-out-quart: cubic-bezier(0.165, 0.84, 0.44, 1);
--ease-out-quint: cubic-bezier(0.23, 1, 0.32, 1);
--ease-out-expo: cubic-bezier(0.19, 1, 0.22, 1);
--ease-out-circ: cubic-bezier(0.075, 0.82, 0.165, 1);
Why it works: Acceleration at the start creates an instant, responsive feeling. The element "jumps" toward its destination then settles in.
Use when elements already on screen need to move or morph. Mimics natural motion like a car accelerating then braking.
/* Sorted weak to strong */
--ease-in-out-quad: cubic-bezier(0.455, 0.03, 0.515, 0.955);
--ease-in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1);
--ease-in-out-quart: cubic-bezier(0.77, 0, 0.175, 1);
--ease-in-out-quint: cubic-bezier(0.86, 0, 0.07, 1);
--ease-in-out-expo: cubic-bezier(1, 0, 0, 1);
--ease-in-out-circ: cubic-bezier(0.785, 0.135, 0.15, 0.86);
Use for hover states and color transitions. The asymmetrical curve (faster start, slower end) feels elegant for gentle animations.