<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script>
document.addEventListener("DOMContentLoaded", () => {
  document.designMode = "on";
  document.addEventListener("DOMNodeRemoved", () => {
    document.documentElement.normalize();
    document.designMode = "off";
  });
  getSelection().collapse(document.querySelector("address").firstChild, 1);
  document.execCommand("insertHorizontalRule");
});
</script>
</head>
<body>
<address>
A
</address>
</body>
</html>
