*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  background: #111;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  overflow: hidden;
  font-family: 'Courier New', monospace;
}

#game {
  display: block;
  image-rendering: pixelated;
  cursor: crosshair;
}