*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: #000; height: 100%; overflow: hidden; }
#app {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
}
#game-canvas {
  display: block;
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}