<ul>
  <li>
    <iframe src="https://www.google.com/maps/embed?pb=!1m18!1m12!1m3!1d212562.02415783118!2d130.09916448090505!3d33.649863916585836!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x3541eda1e9848429%3A0xf60a729936398783!2z56aP5bKh55yM56aP5bKh5biC!5e0!3m2!1sja!2sjp!4v1680168840653!5m2!1sja!2sjp" width="600" height="450" style="border:0;" allowfullscreen="" loading="lazy" referrerpolicy="no-referrer-when-downgrade"></iframe>
  </li>
  <li>
    <iframe width="560" height="315" src="https://www.youtube.com/embed/IqKz0SfHaqI" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>
  </li>
</ul>

ul{
  display: flex;
  gap: 20px;
  padding: 20px;
}

li{
  flex: 1;
}

/* 地図や動画のアスペクト比を指定 */
iframe{
  width: 100%;
  height: 100%;
  aspect-ratio: 16 / 9;
}