W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
#container {
  width: 80%;
  aspect-ratio: 5/2;
  margin: auto;
  border: solid black 2px;
  overflow-x: hidden;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
}

.blue {
  background-color: lightblue;
  height: 65%;
  aspect-ratio: 5/2;
}

.green {
  background-color: lightgreen;
  height: 50%;
  aspect-ratio: 9/2;
}

.blue, .green {
  display: block;
  margin: 5px;
  scroll-snap-align: start none;
}
</style>
</head>
<body>

<h3>CSS scroll-snap-align property, vertical scroll.</h3>
<p>Use scroll wheel or drag the scrollbar vertically inside the container box, let go, and see the scroll-snap-align start effect.</p>
<p>Click on a box, then navigate through the blue and green boxes with the up and down arrow keys.</p>

</body>
</html>

​x
 
<!DOCTYPE html><html><head><style>#container {  width: 80%;  aspect-ratio: 5/2;  margin: auto;  border: solid black 2px;  overflow-x: hidden;  overflow-y: scroll;  scroll-snap-type: y mandatory;}​.blue {  background-color: lightblue;  height: 65%;  aspect-ratio: 5/2;}​.green {  background-color: lightgreen;  height: 50%;  aspect-ratio: 9/2;}​.blue, .green {  display: block;  margin: 5px;  scroll-snap-align: start none;}</style></head><body>​<h3>CSS scroll-snap-align property, vertical scroll.</h3><p>Use scroll wheel or drag the scrollbar vertically inside the container box, let go, and see the scroll-snap-align start effect.</p><p>Click on a box, then navigate through the blue and green boxes with the up and down arrow keys.</p>​<div id="container">  <div class="blue"></div>  <div class="green"></div>  <div class="blue"></div>  <div class="green"></div>  <div class="blue"></div>  <div class="green"></div>