What problem does it solve? Web interfaces often feel stiff and disconnected because animations ignore gesture velocity, cannot be interrupted mid-flight, and lack the physical behavior users expect from touch-driven platforms like iOS. ## Core Features & Use Cases - Gesture-Driven Motion Guidance: Provides concrete rules for pointer tracking, velocity handoff, momentum projection, rubber-banding, and interruptible spring animations using Pointer Events and libraries like Motion or Framer Motion. - Materials, Depth, and Typography: Covers translucent layers with backdrop-filter, hierarchy through material weight, optical sizing, size-specific tracking, and leading for web typography. - Accessibility and Design Foundations: Includes reduced-motion and reduced-transparency handling plus Apple's eight design principles for feedback, wayfinding, and simplicity. - Use Case: When building a draggable bottom sheet in a web app, apply the projection formula and spring parameters (damping 0.8, response 0.3) so a flick throws the sheet to the correct snap point and users can grab it mid-animation. ## Quick Start Ask the AI to review your drag interaction or animation code against Apple fluid interface principles and suggest spring parameters and velocity handoff fixes.
