* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  background: #000;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  overflow: hidden;
}
#game-container { width: 100vw; height: 100vh; }
#game-container canvas { display: block; }