CSS will-change Property - Playground Example

<!DOCTYPE html><html><head><style type="text/css">/* Basic layout */
body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  margin: 0;
  background: linear-gradient(135deg, #f0f4ff, #ffffff);
  color: #0f172a;
}

/* Wrapper */
.wrapper {
  text-align: center;
  padding: 32px;
}

/* Card with will-change hint */
.card {
  width: 280px;
  margin: 24px auto;
  background: #ffffff;
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.08);
  transition: transform 240ms cubic-bezier(.2, .8, .2, 1), opacity 200ms linear, box-shadow 240ms;
  will-change: transform, opacity;
  cursor: pointer;
  outline: none;
}

/* Content inside card */
.card__content {
  padding: 20px;
}

/* Hover and focus states trigger an animation */
.card:hover,
.card:focus {
  transform: translateY(-14px) scale(1.01);
  opacity: 0.98;
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.12);
}

/* Small note */
.note {
  margin-top: 12px;
  font-size: 13px;
  color: #475569;
}

/* Inline code styling */
code {
  background: #f8fafc;
  padding: 2px 6px;
  border-radius: 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, 'Roboto Mono', monospace;
  font-size: 13px;
}</style></head><body><main class='wrapper'>
    <h2>CSS will-change demo</h2>
    <div class='card' tabindex='0' aria-label='Example card'>
      <div class='card__content'>
        <h3>Hover or focus me</h3>
        <p>Hinting the browser with <code>will-change: transform, opacity</code></p>
      </div>
    </div>
    <p class='note'>Tip: Interact with the card to see smoother animations when hints are used.</p>
  </main></body></html>