html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  width: 100%;
  background: black;
  overflow: hidden;
  display: flex;
  justify-content: center;
  align-items: center;
}

canvas {
  width: 100vmin;      /* Makes it visually large */
  height: 100vmin;     /* Maintains square aspect ratio */
  image-rendering: pixelated; /* Keeps crisp pixel look */
  display: block;
}