:root {
  color-scheme: dark;
  background: #000;
}

* {
  box-sizing: border-box;
}

html,
body,
main {
  width: 100%;
  height: 100%;
  margin: 0;
}

body {
  background: #000;
}

main {
  display: grid;
  place-items: center;
}

.triangle {
  display: block;
  width: min(75vmin, 720px);
  height: auto;
}