W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
#container {
  width: 80%;
  aspect-ratio: 2/1;
  margin: auto;
  border: solid black 2px;
  overflow-x: hidden;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
}

.blue {
  background-color: lightblue;
  width: 80%;
  aspect-ratio: 5/2;
}

.green {
  background-color: lightgreen;
  width: 60%;
  aspect-ratio: 2/1;
}

.blue, .green {
  margin: 2px;
  scroll-snap-align: start;
  scroll-margin-top: 0;
}
</style>
</head>
<body>

<h1>Change scroll-margin-top property with JavaScript</h1>

<p>Try first to scroll to see how the scroll snaps on start of elements on y-axis.</p>

<p>Now, click button, click inside the container, and see how scrolling behaviour has changed. The elements now snap on start of element, but with a 20px margin to container on the top side.</p>

</body>
</html>