body {
  background-image: url(../../img/expression-bg3.png);
  color: #fff;
  text-align: center;
  font-family: "Taipei Sans TC Beta", sans-serif;
  padding: 2rem;
}

h1 {
  margin-bottom: 1rem;
}

.game-container {
  max-width: 400px;
  margin: 0 auto;
}

.game-board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  background: rgba(255, 255, 255, 0.05);
  padding: 8px;
  border-radius: 12px;
}

.cell {
  background: rgba(255, 255, 255, 0.1);
  aspect-ratio: 1/1;
  border-radius: 8px;
  font-size: 3rem;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -ms-flex-pack: center;
  justify-content: center;
  cursor: pointer;
  -webkit-transition: background 0.3s;
  transition: background 0.3s;
}

.cell:hover {
  background: rgba(255, 255, 255, 0.2);
}

/* O 顯示為綠色 */
.cell.o-mark {
  color: #2ecc71;
  /* 綠色 */
}

/* X 顯示為紅色 */
.cell.x-mark {
  color: #e74c3c;
  /* 紅色 */
}

/* 贏得比賽時的效果 */
.winning-cell {
  background-color: rgba(255, 255, 255, 0.2);
}

#status {
  margin-top: 1rem;
  font-size: 1.2rem;
}

#restartBtn {
  margin-top: 1rem;
  padding: 0.6rem 1.5rem;
  background: linear-gradient(45deg, #ff00cc, #3333ff);
  border: none;
  border-radius: 8px;
  color: white;
  font-size: 1rem;
  cursor: pointer;
}