CSS scroll-driven animations

The CSS scroll-driven animations module provides functionality that builds on the CSS animations module and Web Animations API. It allows you to animate property values along a scroll-based timeline rather than the default time-based document timeline. This means that you can animate an element by scrolling the element, its scroll container, or its root element, rather than just by the passing of time.

Scroll-driven animations in action

You can define the scroller that controls the animation either by naming the animation or with the scroll function.

<main>
  <div></div>
</main>

css

main {
  scroll-timeline: --mainTimeline;
}

div {
  animation: backgroundAnimation linear;
  animation-timeline: scroll(nearest inline);
}

div::after {
  animation: shapeAnimation linear;
  animation-timeline: --mainTimeline;
}

@layer animations {
  @keyframes backgroundAnimation {
    0% {
      background-color: palegoldenrod;
    }
    100% {
      background-color: magenta;
    }
  }
  @keyframes shapeAnimation {
    0% {
      left: 0;
      top: 0;
      background-color: black;
    }
    50% {
      top: calc(100% - var(--elSize));
      left: calc(50% - var(--elSize));
      background-color: red;
    }
    100% {
      left: calc(100vw - var(--elSize));
      top: 0;
      rotate: 1800deg;
      background-color: white;
    }
  }
}

@layer pageSetup {
  :root {
    --elSize: 50px;
  }
  main {
    height: 90vh;
    overflow: scroll;
    border: 1px solid;
    margin: 5vh auto;
  }
  div {
    height: 400vh;
    width: 400vw;
  }
  div::after {
    content: "";
    border: 1px solid red;
    height: var(--elSize);
    width: var(--elSize);
    position: absolute;
    border-radius: 20px;
    corner-shape: superellipse(-4);
  }
}

@layer noSupport {
  @supports not (scroll-timeline: --mainTimeline) {
    body::before {
      content: "Your browser doesn't support scroll-driven animations.";
      background-color: wheat;
      display: block;
      width: 100%;
      text-align: center;
    }
    body > * {
      display: none;
    }
  }
}

Scroll the element in the inline direction to see its background color change. Scroll it vertically to see the generated content move, spin, and change colors.