<!doctype html>
<body>
<script>
  const SVG_NS = "http://www.w3.org/2000/svg";
  let g = document.createElementNS(SVG_NS, "g");
  g.style.display = "contents";
  document.body.appendChild(g);
  let div = document.createElement('div');
  div.style.width = div.style.height = "100px";
  div.style.backgroundColor = "green";
  g.appendChild(div);
</script>
</body>