css/css-scoping/slotted-with-pseudo-element.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Scoping: pseudo element after ::slotted</title>
<link rel="author" title="Rune Lillesveen" href="mailto:rune@opera.com">
<link rel="help" href="https://drafts.csswg.org/css-scoping/#slotted-pseudo">
<link rel="match" href="slotted-with-pseudo-element-ref.html">
<div id="host1"><span></span></div>
<div id="host2"><span></span></div>
<div id="host3"><span></span></div>
<div id="host4"><span></span></div>
<style>
  #host3 > span::before { content: "PASS" }
</style>
<script>
  function attachShadowWithSlottedStyle(host, styleString) {
    var root = host.attachShadow({mode:"open"});
    root.innerHTML = "<style>"+styleString+"</style><slot></slot>";
  }

  attachShadowWithSlottedStyle(host1, "::slotted(span)::before { content: 'PASS' }");
  attachShadowWithSlottedStyle(host2, "::slotted(span)::after { content: 'PASS' }");
  attachShadowWithSlottedStyle(host3, "::slotted(span)::before { content: 'FAIL'; color: green }");
  attachShadowWithSlottedStyle(host4, `
    ::slotted(span)::before { content: 'PASS'; color: red }
    ::slotted(.foo)::before { color: green }
  `);
  onload = function() {
    host4.offsetTop;
    host4.firstElementChild.classList.add("foo");
  }
</script>