W3Schools Tryit 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: 30px 0;
}
      
#imgDiv > img {
  width: 95%;
  margin: 2px;
  scroll-snap-align: start none;
}
</style>
</head>
<body>

<h3>CSS scroll-padding-block property.</h3>
<p>Drag the scrollbar vertically inside the photo gallery box, let go, and see the scroll-snap effect with snap position start in block direction, and scroll-padding-block 30px at the start of the container. The effect of the scroll-padding-block property value is that the images are offset below the fixed top element.</p>

<div id="container">
  <div id="topDiv">Fixed top element</div>
  <div id="imgDiv">
    <img src="img_chania.jpg" alt="alley" width="460" height="345">
    <img src="img_forest_narrow.jpg" alt="bridge in jungle" width="326" height="400">
    <img src="img_mountains.jpg" alt="mountains" width="600" height="400">
    <img src="img_man_narrow.jpg" alt="man with camera" width="709" height="963">
    <img src="img_5terre.jpg" alt="Cinque Terre" width="600" height="400">
  </div>
</div>

</body>
</html>