background-attachment

background-attachment: scroll;

background-attachment: fixed;

background-attachment: local;

background-attachment: local, scroll;

background-attachment: scroll, local;

<section id="default-example">
  <div id="example-element">
    London. Michaelmas term lately over, and the Lord Chancellor sitting in
    Lincoln's Inn Hall. Implacable November weather. As much mud in the streets
    as if the waters had but newly retired from the face of the earth, and it
    would not be wonderful to meet a Megalosaurus, forty feet long or so,
    waddling like an elephantine lizard up Holborn Hill. London. Michaelmas term
    lately over, and the Lord Chancellor sitting in Lincoln's Inn Hall.
    Implacable November weather. As much mud in the streets as if the waters had
    but newly retired from the face of the earth, and it would not be wonderful
    to meet a Megalosaurus, forty feet long or so, waddling like an elephantine
    lizard up Holborn Hill.
  </div>
</section>

body {
  overflow: scroll;
}

#default-example {
  height: 600px;
}

#example-element {
  max-width: 20rem;
  height: 100%;
  background:
    url("/proxy/developer.mozilla.org/shared-assets/images/examples/lizard.png") right 3rem top 1rem / 15rem
      no-repeat,
    url("/proxy/developer.mozilla.org/shared-assets/images/examples/moon.jpg") center / 10rem;
  color: #ff5454;
  font-size: 1.5em;
  font-weight: bold;
  overflow: auto;
  padding: 20px;
  text-shadow:
    0 0 0.6rem #000,
    0 0 0.6rem #000;
}

/* 关键 属性值 */
background-attachment: scroll;
background-attachment: fixed;
background-attachment: local;

/* 全局 属性值 */
background-attachment: inherit;
background-attachment: initial;
background-attachment: unset;

p {
  background-image: url("star-solid.gif");
  background-attachment: fixed;
}

<p>
  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 {
  background-image: url("star-solid.gif"), url("star-transparent.gif");
  background-attachment: fixed, scroll;
  background-repeat: no-repeat, repeat-y;
}

<p>
  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.
  Suddenly she came upon a little three-legged table, all made of solid glass;
  there was nothing on it except a tiny golden key, and Alice's first thought
  was that it might belong to one of the doors of the hall; but, alas! either
  the locks were too large, or the key was too small, but at any rate it would
  not open any of them. However, on the second time round, she came upon a low
  curtain she had not noticed before, and behind it was a little door about
  fifteen inches high: she tried the little golden key in the lock, and to her
  great delight it fitted!
</p>