body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    text-align: center;
    background: white;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    padding: 20px;
    border-radius: 8px;
}

.grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    gap: 5px;
    margin: 20px 0;
}

.cell {
    width: 40px;
    height: 40px;
    font-size: 24px;
    text-align: center;
    outline: none;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.cell:focus {
    border-color: #007BFF;
}

button {
    padding: 10px 15px;
    margin: 5px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    background-color: #007BFF;
    color: white;
    font-size: 16px;
}

button:hover {
    background-color: #0056b3;
}

.message {
    margin-top: 20px;
    font-size: 18px;
    color: green;
}