html,
body {
  margin: 0;
  height: 100%;
  background: #000;
  overflow: hidden;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
}

/* 480x800 の縦長キャンバスを、比率を保ったまま画面いっぱいに拡縮する */
#game {
  display: block;
  width: min(100vw, calc(100dvh * 0.6));
  height: auto;
  aspect-ratio: 3 / 5;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
  -webkit-tap-highlight-color: transparent;
}