CSS Animation Fundamentals
CSS animations use @keyframes rules to define the stages of an animation and the animation shorthand property to apply them. Keyframes specify what styles the element should have at given points during the sequence. The animation property ties the keyframes to an element and controls duration, timing, delay, repetition, direction, and fill behavior.
Choosing the Right Timing Function
Timing functions determine the acceleration curve of an animation. Linear creates constant speed; ease starts slow, speeds up, then slows down; ease-in starts slow; ease-out slows toward the end; ease-in-out combines both. The right choice depends on the context; entrance animations often benefit from ease-out while exit animations work well with ease-in.
Performance Considerations
Animations that change transform and opacity are hardware-accelerated and perform best. Animating layout properties like width, height, or margin triggers expensive reflows. Stick to transforms for movement, scaling, and rotation. Use will-change sparingly to hint the browser about upcoming animations without over-allocating GPU memory.
Accessibility and Reduced Motion
Always respect the prefers-reduced-motion media query. Users who experience motion sickness or have vestibular disorders can enable reduced motion in their operating system. Wrap your animations in a @media (prefers-reduced-motion: no-preference) query or provide a simpler fallback to ensure your site is usable for everyone.
