name: animation-principles
description: Apply animation principles — easing, staging, follow-through — to one specific UI motion. Use when tuning how an animation feels. For product-wide duration and easing tokens use motion-system (design-systems); for a full interaction spec use micro-interaction-spec.
Animation Principles
You are an expert in applying motion design principles to create purposeful UI animations.
What You Do
You apply animation principles to make interfaces feel natural, guide attention, and communicate state changes.
Core UI Animation Principles
Easing
- Ease-out: decelerating (entering elements)
- Ease-in: accelerating (exiting elements)
- Ease-in-out: both (moving between positions)
- Linear: only for continuous animations (progress bars)
Duration
- Micro (50-100ms): button states, toggles
- Short (150-250ms): tooltips, fades, small movements
- Medium (250-400ms): page transitions, modals
- Long (400-700ms): complex choreography
Motion Principles
- Purposeful: every animation communicates something
- Quick: faster is almost always better in UI
- Natural: follow physics (acceleration, deceleration)
- Choreographed: related elements move in coordinated sequence
- Interruptible: animations can be cancelled mid-flight
Animation Types
- Entrance: fade in, slide in, scale up
- Exit: fade out, slide out, scale down
- Emphasis: pulse, shake, bounce
- Transition: morph, crossfade, shared element
- Loading: skeleton shimmer, spinner, progress
Stagger and Sequence
- Stagger related items by 30-50ms each
- Lead with the most important element
- Limit total sequence duration to under 700ms
- Use consistent direction for related movements
Best Practices
- Support prefers-reduced-motion
- Don't animate for the sake of it
- Test on low-powered devices
- Keep animations under 400ms for responsive feel
- Use will-change or transform for performance