W3School TIY 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>

<h1>CSS scroll-snap-align 属性，垂直滚动</h1>

<p>使用滚轮或在容器框内垂直拖动滚动条，然后松开，观察 scroll-snap-align start（滚动吸附对齐开始）的效果。</p>

<p>点击一个框，然后使用上下箭头键在蓝色和绿色框之间导航。</p>

</body>
</html>