<!DOCTYPE html>
<meta charset="utf-8" />
<title>Dialog-Popover appearance</title>
<link rel="author" href="mailto:masonf@chromium.org">

<p>Both dialogs should have the same shades of background.</p>
<p>The popover should have a completely-transparent ::backdrop.</p>
<dialog popover id=d1>This is a modal dialog</dialog>
<dialog popover id=d2>This is a dialog popover</dialog>

<style>
  dialog {
    left: 50px;
    right: auto;
    bottom: auto;
  }
  #d1 {top:100px;}
  #d2 {top:150px;}
  /* Force backdrop to spec: */
  #d1::backdrop {
    /* https://html.spec.whatwg.org/multipage/rendering.html#flow-content-3 */
    background-color: rgba(0, 0, 0, 0.1);
  }
  #d2::backdrop {
    /* When shown as a popover, backdrop must be transparent */
    background-color: transparent;
  }
</style>

<script>
  document.getElementById('d1').showModal();
  document.getElementById('d2').showPopover();
</script>
