<!DOCTYPE html>
<style>
body {
margin: 0;
height: 2000px;
overflow: hidden; /* hide scrollbars */
overflow-anchor: none;
}
#spacer {
height: 200px;
}
.container {
background-color: red;
width: 200px;
height: 400px;
outline: 2px solid black;
}
.box {
width: 200px;
height: 200px;
}
.sticky {
position: sticky;
top: 0px;
background-color: green;
}
</style>
<script>
function doTest()
{
window.scrollTo(0, 200);
// When the spacer's height is changed the sticky container moves up which should now
// require sliding the sticky box down.
document.getElementById('spacer').style.height = '0px';
}
window.addEventListener('load', doTest, false);
</script>
<div id="spacer"></div>
<div class="container">
<div class="sticky box"></div>
</div>