css/css-scoping/keyframes-002.html

<!doctype html>
<title>CSS Test: @keyframes from the document should apply in the shadow tree.</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<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">

<style>
@keyframes myanim {
  from { background: red; }
  to { background: red; }
}
</style>
<div id="host"></div>
<script>
test(function() {
  host.attachShadow({ mode: "open" }).innerHTML = `
    <style>
      #in-shadow {
        width: 100px;
        height: 100px;
        background: blue;
        animation: myanim 10s infinite;
      }
    </style>
    <div id="in-shadow"></div>
  `;

  assert_equals(host.shadowRoot.getElementById('in-shadow').getAnimations().length, 1);
}, "@keyframes from the document should apply in the shadow tree");
</script>