Advanced CSS Animation Techniques with Claude Code

Master Advanced CSS Animation Techniques

Let’s go beyond basic transitions and keyframes and look at how to efficiently implement practical CSS animation techniques with Claude Code.

Scroll-Driven Animations

> Implement scroll-driven animations using CSS only.
> Use the Scroll-driven Animations API.

/* Scroll progress bar */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: var(--color-accent);
  transform-origin: left;
  animation: scaleProgress linear;
  animation-timeline: scroll();
}

@keyframes scaleProgress {
  from { transform: scaleX(0); }
  to   { transform: scaleX(1); }
}

/* Element reveal animation */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  animation: fadeInUp linear both;
  animation-timeline: view();
  animation-range: entry 0% entry 100%;
}

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

View Transitions API

// Page transition animations
async function navigateWithTransition(url: string) {
  if (!document.startViewTransition) {
    window.location.href = url;
    return;
  }

  const transition = document.startViewTransition(async () => {
    const response = await fetch(url);
    const html = await response.text();
    const parser = new DOMParser();
    const doc = parser.parseFromString(html, 'text/html');
    document.body.innerHTML = doc.body.innerHTML;
    document.title = doc.title;
    window.history.pushState({}, '', url);
  });

  await transition.finished;
}

/* Customizing View Transitions */
::view-transition-old(root) {
  animation: fade-out 0.3s ease-out;
}

::view-transition-new(root) {
  animation: fade-in 0.3s ease-in;
}

@keyframes fade-out {
  from { opacity: 1; transform: scale(1); }
  to   { opacity: 0; transform: scale(0.95); }
}

@keyframes fade-in {
  from { opacity: 0; transform: scale(1.05); }
  to   { opacity: 1; transform: scale(1); }
}

/* Per-element transitions */
.card-image {
  view-transition-name: card-hero;
}

::view-transition-old(card-hero),
::view-transition-new(card-hero) {
  animation-duration: 0.4s;
}

Complex Keyframe Animations

/* Typing animation */
.typing {
  overflow: hidden;
  border-right: 2px solid var(--color-accent);
  white-space: nowrap;
  animation:
    typing 3s steps(30) 1s forwards,
    blink 0.75s step-end infinite;
  width: 0;
}

@keyframes typing {
  to { width: 100%; }
}

@keyframes blink {
  50% { border-color: transparent; }
}

/* Particle animation */
.particle {
  --delay: 0s;
  --x: 0px;
  --y: 0px;
  position: absolute;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-accent);
  animation: particle 1.5s var(--delay) ease-out infinite;
}

@keyframes particle {
  0% {
    opacity: 1;
    transform: translate(0, 0) scale(1);
  }
  100% {
    opacity: 0;
    transform: translate(var(--x), var(--y)) scale(0);
  }
}

Performance Optimization

/* Take advantage of GPU acceleration */
.animated-element {
  /* Only animate transform and opacity */
  will-change: transform, opacity;
  transform: translateZ(0); /* Promote to its own layer */
}

/* Release will-change after the animation is done */
.animated-element.done {
  will-change: auto;
}

/* Avoid layout shifts */
.expand-animation {
  /* Use max-height instead of height */
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.expand-animation.open {
  max-height: 500px; /* large enough */
}

Accessibility

/* Respect the user's reduced-motion preference */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .typing {
    width: 100%;
    border-right: none;
  }

  .progress-bar {
    animation: none;
    transform: scaleX(1);
  }
}

Summary

For advanced CSS animations, striking a balance between performance optimization and accessibility is essential. With Claude Code, you can accurately implement modern features like the View Transitions API and scroll-driven animations. Combined with CSS variables, you can also manage animation parameters flexibly. For View Transitions API details, see Chrome Developers.