<!DOCTYPE html>
<html>
<head>
<style>
* { z-index: -1; }
html { position: sticky; }
</style>
<script>
  onload = () => {
    document.querySelector("dialog").showModal();
  }
</script>
</head>
<body>
<dialog>
PASS if this displays and doesn't crash
</dialog>
</body>
</html>
