How to animate sections in pure CSS when scrolling the page?

Tags: html,css,html5,css3

Problem :

I am looking for a way to animate (with @keyframes, transform...) some elements when the user scrolls the page. For example:

  • When offset is 0: div has height: 100px.
  • When offset is between 0 and 100: div is height: 50px and color: blue.
  • And so on...

Is is possible using pure CSS? If it is not, what are the most efficient ways to do it with HTML or Javascript?

Solution :

The most efficient way to animate an element's style properties depending on scroll position will probably be to add a class with a scroll function:

Working Example

myID = document.getElementById("myID");

var myScrollFunc = function() {
  var y = window.scrollY;
  if (y > 500) {
    // = "blue"; // you can add individual styles 
    myID.className = "blue" // or add classes
  } else {
    // = "red";
    myID.className = "red"

window.addEventListener("scroll", myScrollFunc);
body {
  height: 1100px;
#myID {
  position: fixed;
  height: 100px;
  line-height: 20px;
  transition: all 1s;
.blue {
  background: blue;
  animation: myAnimation 1s both;
.red {
  background: red;
@keyframes myAnimation {
  0% {
    border-radius: 0px;
    line-height: 10px;
  100% {
    border-radius: 100%;
    line-height: 100px;
<div id="myID" class="red">Hello world</div>



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