* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
  background: #05060f;
  overflow: hidden;
}

#app {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
}

#game {
  display: block;
  /* 画面に収まる最大サイズで 2:3 の比率を保つ */
  height: min(100vh, 150vw);
  width: auto;
  aspect-ratio: 2 / 3;
  background: #000;
  box-shadow: 0 0 40px rgba(80, 120, 255, 0.25);
  touch-action: none;
  image-rendering: pixelated;
}