<!DOCTYPE html>
<link rel=author href="mailto:jarhar@chromium.org">
<link rel=help href="https://github.com/w3c/csswg-drafts/issues/8389">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<dialog>
  <button>button</button>
</dialog>

<style>
dialog.ready {
  transition: display 500ms;
}
</style>

<script>
promise_test(async () => {
  const dialog = document.querySelector('dialog');
  const button = document.querySelector('button');

  dialog.showModal();
  button.blur(); // Dialog initial focus focused the button
  dialog.classList.add('ready');

  dialog.close();
  await new Promise(resolve => requestAnimationFrame(resolve));
  button.focus();

  assert_not_equals(document.activeElement, button, 'Inert elements should not be focusable.');
}, 'Elements which are transitioning to display:none should be inert.');
</script>
