css-animation-patterns

Este extracto es una copia guardada durante la revisión. La fuente externa contiene la versión completa y actual.

---
name: css-animation-patterns
description: >
  CSS animations, transitions, keyframes, and modern motion APIs. Use when adding animations, transitions,
  scroll-driven effects, or view transitions. Use for css-animation, transition, keyframes, view-transitions,
  scroll-animation, transform, motion-preference, animation-timeline.
license: MIT
metadata:
  author: oakoss
  version: '1.0'
  source: 'https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_animations'
user-invocable: false
---

# CSS Animation Patterns

## Overview

CSS animations and transitions provide hardware-accelerated motion for web interfaces using keyframes, transitions, transforms, and modern scroll-driven and view transition APIs. Animate only composite properties (`transform`, `opacity`, `filter`) for smooth 60fps performance, and always respect `prefers-reduced-motion`.

The browser rendering pipeline has four stages: Style, Layout, Paint, and Composite. Animating composite-only properties skips Layout and Paint entirely, running on the GPU compositor thread. This is the single most important performance principle for CSS animation.

Modern CSS adds two powerful APIs: **scroll-driven animations** link keyframe progress to scroll position or element visibility instead of time, and the **View Transitions API** creates snapshot-based animated transitions between DOM states for both SPAs and MPAs.

**When to use:** Element state changes, page transitions, scroll-linked effects, loading indicators, micro-interactions, route change animations, reveal-on-scroll patterns, parallax effects, progress indicators tied to scroll.

**When NOT to use:** Complex physics simulations (use a JS animation library), canvas/WebGL rendering, animations requiring frame-by-frame scripted control (use Web Animations API directly), highly interactive drag-and-drop (use pointer events with JS).

## Browser Support Summary

| Feature                               | Chrome | Firefox | Safari |
| ------------------------------------- | ------ | ------- | ------ |
| Transitions, keyframes, transforms    | Full   | Full    | Full   |
| Individual transform properties       | 104+   | 72+     | 14.1+  |
| `@starting-style`                     | 117+   | 129+    | 17.5+  |
| `transition-behavior: allow-discrete` | 117+   | 129+    | 17.4+  |
| Scroll-driven animations              | 115+   | Not yet | 26+    |
| Same-document view transitions        | 111+   | 144+    | 18+    |
| Cross-document view transitions       | 126+   | Not yet | 18+    |
| `view-transition-class`               | 125+   | 144+    | 18+    |

Use `@supports` for progressive enhancement with newer features. Always provide a functional non-animated fallback.

## Quick Reference

| Pattern               | API                                             | Key Points                                                  |
| --------------------- | ----------------------------------------------- | ----------------------------------------------------------- |
| State transition      | `transition: property duration easing`          | Triggers on property change, composite-only for performance |
| Discrete transition   | `transition-behavior: allow-discrete`           | Enables transitions on `display`, `visibility`              |
| Entry animation       | `@starting-style { ... }`                       | Initial state for elements appearing in DOM                 |
| Keyframe animation    | `@keyframes name` + `animation` shorthand       | Multi-step sequences, supports `forwards` fill mode         |
| Transform             | `transform: translate() scale() rotate()`       | GPU-composited, no layout recalculation                     |
| Individual transforms | `translate`, `rotate`, `scale`                  | Independently animatable with different timings             |
| Scroll progress       | `animation-timeline: scroll()`                  | Links animation to scroll position of a container           |
| View progress