* {
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background-color: #f0f2f5;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.container {
  text-align: center;
  background: white;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

h1 {
  color: #333;
  margin-bottom: 10px;
}

#status {
  font-size: 1.2rem;
  margin-bottom: 20px;
  font-weight: bold;
  color: #555;
}

/* Tọa độ bàn cờ 3x3 */
.board {
  display: grid;
  grid-template-columns: repeat(3, 100px);
  grid-template-rows: repeat(3, 100px);
  gap: 8px;
  margin: 0 auto 20px auto;
}

.cell {
  background-color: #e9ecef;
  border-radius: 8px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 2.5rem;
  font-weight: bold;
  cursor: pointer;
  transition: background 0.2s;
}

.cell:hover {
  background-color: #dee2e6;
}

/* Màu sắc đại diện cho X và O */
.cell.x {
  color: #e74c3c;
}

.cell.o {
  color: #3498db;
}

button {
  padding: 10px 20px;
  font-size: 1rem;
  font-weight: bold;
  color: white;
  background-color: #2ecc71;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: opacity 0.2s;
}

button:hover {
  opacity: 0.9;
}