htmz, a low power tool for html

Minified:

<iframe hidden name=htmz onload="setTimeout(()=>document.querySelector(contentWindow.location.hash||null)?.replaceWith(...contentDocument.body.childNodes))"></iframe>

Deminified:

<script>
  function htmz(frame) {
    // Write your extensions here

    // Remove setTimeout to let the browser autoscroll content changes into view
    setTimeout(() =>
      document
        .querySelector(frame.contentWindow.location.hash || null)
        ?.replaceWith(...frame.contentDocument.body.children)
    );
  }
</script>
<iframe hidden name=htmz onload="htmz(this)"></iframe>

Source: htmz

This is powerfully simple. Used well, this eliminates the need for much more complex solutions.