:root {
  color-scheme: dark;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

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

body {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: 0;
}

iframe {
  width: 100%;
  height: 100%;
  border: 0;
  margin: 0;
  display: block;
}