Modern web interfaces rely on declarative, GPU-accelerated motion to guide attention without
compromising performance or accessibility. Using native browser APIs —
animation-timeline: scroll(), view(), and
document.startViewTransition() — teams can move animation logic off the main
thread entirely, achieving deterministic frame timing that was once only possible with
heavyweight JavaScript libraries.
This site is a technical reference for frontend developers and motion engineers who need to
implement, debug, and optimise CSS scroll-driven animations and page transitions in production.
Every pattern includes compositor-safe CSS, progressive enhancement strategies, framework
examples for React, Vue, and Svelte, and prefers-reduced-motion support throughout —
plus DevTools profiling workflows and Core Web Vitals guidance for keeping animated
interfaces inside the 16 ms frame budget.
Recently expanded: how a timeline decides which scroll container drives it, a full set of media and gallery patterns, GPU memory and layer budgeting, engine-by-engine performance behaviour, and the focus and announcement work that animation APIs deliberately leave to you.
scroll() and view() work
prefers-reduced-motion correctly
scroll() vs view() — choosing the right timeline function
none — the five causes, in order
WCAG 2.2 compliance, prefers-reduced-motion architecture, motion scaling
strategies, and compositor-safe patterns that work for all users on all devices.
Browser rendering pipelines, compositor thread isolation, scroll-timeline architecture, View Transition lifecycle internals, cross-browser support, and fallback strategies.
Production-ready patterns: scroll progress indicators, parallax, SPA page swaps, sticky headers, element morphing — with CSS, React, Vue, and Svelte examples.
Measure what you ship: DevTools profiling workflows, compositor-safe property choices,
will-change budgeting, and the Core Web Vitals impact of animated interfaces.