W3School TIY Editor

<!DOCTYPE html>
<html>
<head>
<style>
#container {
  width: 80%;
  aspect-ratio: 2/1;
  margin: auto;
  border: solid black 2px;
  overflow-x: scroll;
  overflow-y: hidden;
  scroll-snap-type: x mandatory;
  writing-mode: vertical-rl;
  scroll-padding-block: 20px 0;
}

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

.green {
  background-color: lightgreen;
  height: 80%;
  aspect-ratio: 4/5;
}

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

<h1>CSS scroll-padding-block 属性</h1>

<p>当 writing-mode 属性值设置为 vertical-rl 时，元素在块级方向上的起点从顶部变为右侧，这也会影响 scroll-padding-block 属性。</p>

<p>在此例中，块级方向的吸附位置设置为起点位置，因此焦点元素应该吸附到距离容器顶部 20px 的位置。但由于 writing-mode 的值，焦点元素实际上在子元素与容器右侧之间有一个 20px 的偏移距离。</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>