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.
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. Source: oakoss/agent-skills.