简单的例子

HTML

<!-- Learn about this code on MDN: https://developer.mozilla.org/zh-CN/docs/Web/CSS/background-attachment -->

<p class="local">
  There were doors all round the hall, but they were all locked; and when
  Alice had been all the way down one side and up the other, trying every
  door, she walked sadly down the middle, wondering how she was ever to
  get out again.
</p>

<p class="scroll">
  There were doors all round the hall, but they were all locked; and when
  Alice had been all the way down one side and up the other, trying every
  door, she walked sadly down the middle, wondering how she was ever to
  get out again.
</p>

CSS

p {
  background-image: url("https://mdn.mozillademos.org/files/12057/starsolid.gif");
  width: 100px;
  height: 100px;
  overflow-y: scroll;
}

.local {
  background-attachment: local;
}

.scroll {
  background-attachment: scroll;
}