What problem does it solve? Deciding whether and how to animate a UI element is error-prone: wrong easings, sluggish durations, layout-thrashing properties, and missing reduced-motion support make interfaces feel cheap. This Skill turns a motion request into a reviewed implementation by walking a fixed decision sequence before writing any code. ## Core Features & Use Cases - Gated build sequence: Decides first whether the element should animate at all (frequency tiers), names the motion's purpose, then picks the cheapest tool — CSS transition, @starting-style, CSS animation, WAAPI, or Motion. - Opinionated ingredient tables: Fixed easing curves (cubic-bezier(0.23, 1, 0.32, 1) and others), duration budgets per component type, spring configs, and a never-ship blocklist (scale(0), ease-in, transition: all, ungated hover). - Ready-made recipes: RECIPES.md provides implementations for button press, popover, tooltip, modal, drawer, toast, accordion, stagger, hold-to-confirm, tab indicator, scroll reveal, and drag-to-dismiss. - Use Case: Ask to animate a dropdown menu, and get a transform-origin-anchored scale-and-fade at 200ms with reduced-motion and hover gating included, plus a one-line rationale for each choice. ## Quick Start Animate the settings modal so it scales in from 0.96 with a fading backdrop, following the build sequence and shipping reduced-motion support.