W3School TIY Editor

<!DOCTYPE html>
<html>
<head>
<style>
#container {
  position: relative;
  width: 60%;
  aspect-ratio: 2/3;
  margin: auto;
  border: solid black 2px;
}

#topDiv {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 25px;
  z-index: 1;
  background-color: rgba(0, 0, 0, 0.8);
  color: white;
}

#imgDiv {
  position: absolute;
  inset: 0 0 0 0;
  padding-top: 40px;
  overflow-x: hidden;
  overflow-y: scroll;
  scroll-snap-type: y mandatory;
  scroll-padding-block-start: 30px;
}
      
#imgDiv > img {
  width: 95%;
  margin: 2px;
  scroll-snap-align: start none;
}
</style>
</head>
<body>

<h1>CSS scroll-padding-block-start 属性</h1>

<p>在图片库框内垂直拖动滚动条，然后松开，观察在块方向设置为开始吸附位置，且容器设置了 30px 的 scroll-padding-block-start 时的滚动吸附效果。scroll-padding-block-start 属性值的作用是使图片相对于固定的顶部元素向下偏移。</p>

<div id="container">
  <div id="topDiv">Fixed top element</div>
  <div id="imgDiv">
    <img src="/i/photo/beijing.jpg" alt="Beijing" width="600" height="400">
    <img src="/i/photo/dancer.png" alt="Dancer" width="500" height="749">
    <img src="/i/photo/wuhan.jpg" alt="Wuhan" width="600" height="400">
    <img src="/i/photo/tulip.jpg" alt="Tulip" width="300" height="300">
    <img src="/i/photo/hangzhou.jpg" alt="Hangzhou" width="600" height="400">
  </div>
</div>

</body>
</html>