W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
#container {
  width: 40%;
  aspect-ratio: 2/3;
  margin: auto;
  border: solid black 2px;
  overflow-x: hidden;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
  white-space: nowrap;
  writing-mode: vertical-rl;
  scroll-padding-inline-start: 20px;
}

.blue {
  background-color: lightblue;
  width: 95%;
  aspect-ratio: 5/6;
}

.green {
  background-color: lightgreen;
  width: 80%;
  aspect-ratio: 3/4;
}

.blue, .green {
  display: inline-block;
  margin: 2px;
  scroll-snap-align: none start;
}
</style>
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<body>

<h3>CSS scroll-padding-inline-start property.</h3>
<p>With the writing-mode property value set to vertical-rl the start of the element in the inline direction is changed from left side to the top, and this also affects the scroll-padding-inline-start property.</p>
<p>In this example, snap position is set to start in the inline direction, so the element in focus should snap into place with a 20px distance to the left of the container. But instead, because of the writing-mode value, the element in focus is offset by a 20px distance between child element and the top of the container.</p>

<div id="container">
  <div class="blue">Blue</div>
  <div class="green">Green</div>
  <div class="blue">Blue</div>
  <div class="green">Green</div>
  <div class="blue">Blue</div>
  <div class="green">Green</div>
  <div class="blue">Blue</div>
</div>

</body>
</html>