<iframe width="800" height="600" src="https://www.youtube.com/embed/LuIHEev-yVg" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen style="--aspect-ratio: 800 / 600"></iframe>

@import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100vw;
  min-height: 100vh;
  font-family: "Exo", Arial, sans-serif;
  background-color: #222;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.5rem;
  gap: 10px;
  padding: 10px;
}

iframe {
  border: 10px solid #f90;
  aspect-ratio: var(--aspect-ratio);
  width: 50%;
  height: auto;
}

@supports (aspect-ratio: attr(width number) / 1) {
  iframe[width][height] {
    aspect-ratio: attr(width number) / attr(height number);
  }
}