async function togglePictureInPicture() {
  // Close Picture-in-Picture window if any.
  if (documentPictureInPicture.window) {
    documentPictureInPicture.window.close();
    return;
  }

  // Open a Picture-in-Picture window.
  const pipWindow = await documentPictureInPicture.requestWindow({
    initialAspectRatio: 640 / 360,
    copyStyleSheets: true,
  });

  // Move video to the Picture-in-Picture window.
  const video = document.querySelector("#video");
  pipWindow.document.body.append(video);

  // Listen for the PiP closing event to move the video back.
  pipWindow.addEventListener("unload", (event) => {
    const videoContainer = document.querySelector("#videoContainer");
    const pipVideo = event.target.querySelector("#video");
    videoContainer.append(pipVideo);
  });
}