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

html,
body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #2b2b3a;
  /* スクロール・ズーム・長押しメニュー・選択を防ぐ */
  touch-action: none;
  overscroll-behavior: none;
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
  -webkit-tap-highlight-color: transparent;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  /* iPhone のノッチ・ホームバーを避ける */
  padding: env(safe-area-inset-top) env(safe-area-inset-right)
    env(safe-area-inset-bottom) env(safe-area-inset-left);
  height: 100dvh;
}

canvas {
  display: block;
  touch-action: none;
  border-radius: 8px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

@media (max-width: 500px) {
  canvas {
    border-radius: 0;
    box-shadow: none;
  }
}