html,
body {
  margin: 0;
  height: 100%;
  background: #000;
}

body {
  min-height: 100dvh;
  display: grid;
  place-items: center;
}

main {
  display: grid;
  place-items: center;
  width: 100%;
  min-height: 100dvh;
}

video {
  display: block;
  width: min(100vw, calc(100dvh * 9 / 16));
  height: auto;
  aspect-ratio: 9 / 16;
  background: #000;
}