html, body {
  margin: 0;
  height: 100%;
  background: #000000;
  overflow: hidden;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  container-type: size;
}
#stage {
  display: block;
  aspect-ratio: 1;
  width: min(100cqw, 100cqh);
  height: min(100cqw, 100cqh);
  max-width: 100%;
  max-height: 100%;
  background: #111111;
}