css/css-scoping/shadow-fallback-dynamic-005.html

<!doctype html>
<title>CSS Scoping Module Level 1 - Dynamic fallback content</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="help" href="https://drafts.csswg.org/css-scoping/#selectors-data-model">
<link rel="match" href="reference/green-box.html"/>
<p>Test passes if you see a single 100px by 100px green box below.</p>
<div id="host">
  <div slot="myslot" style="width: 100px; height: 100px; background: green"></div>
</div>
<script>
  let root = host.attachShadow({ mode: "open" });
  root.innerHTML = `
    <slot name="myslot"></slot>
    <slot name="myotherslot">
      FAIL
    </slot>
  `;
  document.body.offsetTop;
  host.firstElementChild.setAttribute("slot", "myotherslot");
</script>