* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  background: #1a1a2e;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  font-family: system-ui, sans-serif;
  touch-action: manipulation;
}

canvas {
  display: block;
  cursor: pointer;
  /* スマホでは全画面。横長画面 (PC等) では縦横比を最大3:4に制限して中央寄せ */
  width: min(100vw, 75vh);
  height: 100vh;
  /* dvh対応ブラウザ (iOS Safariのアドレスバー分を除いた高さ) */
  width: min(100dvw, 75dvh);
  height: 100dvh;
}