.game-container {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    margin-bottom: 20px;
}

.btn-secondary {
    background-color: #e0e0e0;
    color: #333;
}

.btn-secondary:hover {
    background-color: #d5d5d5;
}

/* Hiển thị bàn cờ dạng lưới (Grid) */
.board {
    display: grid;
    background-color: #board-bg;
    border: 2px solid #ccc;
}

/* Từng ô cờ */
.cell {
    width: 30px;
    height: 30px;
    background-color: #fff;
    border: 1px solid #ddd;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 20px;
    font-weight: bold;
    cursor: pointer;
}

.cell:hover {
    background-color: #f9f9f9;
}

/* Màu cho X và O */
.x { color: #e74c3c; }
.o { color: #3498db; }