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