css/css-transforms/containing-block-dynamic-1-ref.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS transforms: Creating containing block for fixed positioned elements</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Mozilla" href="http://www.mozilla.org/">
<style>
  html, body { margin: 0; padding: 0 }
  #fixedmoves {
    position: absolute;
    top: 150px;
    left: 150px;
    background: green;
    height: 100px;
    width: 100px;
  }
</style>
<body>
  <div id="fixedmoves"></div>
</body>