npx skills add ...
npx skills add dylantarre/animation-principles --skill state-changes
Use when elements transform in place - toggle switches, expanding accordions, checkbox animations, button states, or any transformation without entering/exiting.
npx skills add dylantarre/animation-principles --skill state-changes
Apply Disney's 12 principles when elements transform without leaving.
Squash & Stretch: Elements compress before expanding. A toggle switch squashes 5% before sliding.
Anticipation: Wind up before the change. Slight reverse movement (2-3px) before expanding.
Staging: Keep transformations centered on user focus. Don't let state changes distract from the interaction point.
Straight Ahead vs Pose-to-Pose: Define exact states. Button has rest, hover, active, disabled - each precisely designed.
Follow Through & Overlapping: Parts transform at different rates. Icon rotates before label fades in.
Slow In/Slow Out: Use ease-in-out for bidirectional changes: cubic-bezier(0.4, 0, 0.2, 1).
Arcs: Rotating elements follow natural arcs. Chevrons rotate on their center point, not linearly.
Secondary Action: Pair the primary change with supporting motion. Toggle sliding + color shift + icon swap.
Timing:
Exaggeration: Overshoot slightly on state changes. Toggle goes 2px past, then settles.
Solid Drawing: Maintain element integrity during transformation. No distortion that breaks visual consistency.
Appeal: State changes should feel satisfying. Users clicked with intent - reward that intent.
| State Change | Duration | Easing | Notes |
|---|---|---|---|
| Checkbox | 150ms | ease-out | Tick draws in |
| Toggle Switch | 200ms | ease-in-out | Overshoot slightly |
| Radio Button | 150ms | ease-out | Scale in from center |
| Accordion | 250ms | ease-in-out | Height + rotation |
| Tab Switch | 200ms | ease-in-out | Indicator slides |
| Button Active | 100ms | ease-out | Scale to 0.97 |
| Card Expand | 300ms | ease-in-out | All properties together |
State changes are reversible. The animation to state B should be the inverse of animation to state A. Test both directions.
.accordion-content {
display: grid;
grid-template-rows: 0fr;
transition: grid-template-rows 250ms ease-in-out;
}
.accordion.open .accordion-content {
grid-template-rows: 1fr;
}