html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background-color: #000;
  display: flex;
  flex-direction: column;
}

#gameContainer {
  position: relative;
  width: 100%;
  max-width: 800px;
  aspect-ratio: 4 / 3;
  margin: 0 auto;
}

canvas {
  width: 100%;
  height: 100%;
  display: block;
  background: #a3d5ff;
  touch-action: none;
}

#resetButton, #gameResetButton {
  top: 10px;
  font-size: 18px;
  padding: 6px 12px;
  background-color: #fff;
  border: 1px solid #888;
  cursor: pointer;
}

#resetButton {
  left: 150px;
}

#gameResetButton {
  left: 320px;
}

#timer {
  position: absolute;
  font-family: sans-serif;
  z-index: 1;
  font-size: 24px;
  color: #fff; /* 白文字に変更 */
  right: 10px;
  top: 10px;
}

#countdown {
  position: absolute;
  font-family: sans-serif;
  z-index: 2;
  font-size: 72px;
  color: #fff;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

#gameOver {
  position: absolute;
  font-family: sans-serif;
  z-index: 2;
  font-size: 48px;
  color: #fff;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}