title: How can I move a div on scroll?
body: <p>I have to move a div when the the user scrolls, but need to use pure JavaScript.</p>
  <p><code>position: fixed;</code> will not work with the layout. The div's original position is relative to something else. Is there a simple implementation using an event like <code>onscroll</code>, to detect how many pixels the page moved up or down, and change the position of the div accordingly?</p>
  <p>The div only needs to move vertically. So if I can detect how many pixels the page has moved I can just add or subtract that to the location of the div.</p>