What problem does it solve? Web interfaces often feel stiff because animations are pre-scripted, non-interruptible, and disconnected from user gestures. This Skill translates Apple's WWDC design guidance into concrete web techniques so interfaces respond instantly, track gestures 1:1, and move with physical momentum. ## Core Features & Use Cases - Spring-based motion: Replaces fixed-duration CSS transitions with interruptible springs using damping ratio and response parameters, including concrete values Apple ships for sheets, rotations, and repositioning. - Gesture engineering: Covers pointer tracking with velocity history, velocity handoff at release, momentum projection to predict flick landing points, and rubber-banding at boundaries. - Materials, typography, and accessibility: Guides translucent layers with backdrop-filter, size-specific tracking and leading, and reduced-motion/reduced-transparency adaptations. - Use Case: When building a draggable bottom sheet in React, use this Skill to implement 1:1 pointer tracking, project the flick velocity to choose the snap point, and hand off release velocity into a spring so the gesture flows seamlessly into the animation. ## Quick Start Ask the agent to review or build a gesture-driven UI component, such as a swipeable card or modal sheet, using Apple-style spring physics and interruptible animations.
