iframe.html?blue"></iframe>
<script>
async function runTest() {
  let frame = document.getElementById("inner");

  await document.startViewTransition(() => {
    document.documentElement.style.background = "orange";
    frame.style.border = "1px solid black";
  }).ready;

  frame.contentWindow.postMessage("checkrendering");
  await waitForMessage("rendered");

  frame.src = "resources/root-element-transition-iframe.html?grey";
  await waitForMessage("transition");

  takeScreenshot();
}
onload = () => reque