body {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: Arial, sans-serif;
    background-color: #f7f7f7;
    margin: 0;
    padding: 20px;
}

#sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, 50px);
    gap: 2px;
    border: 2px solid #333;
    margin-bottom: 20px;
}

#sudoku-board input {
    width: 48px;
    height: 48px;
    text-align: center;
    font-size: 18px;
    border: 1px solid #999;
    box-sizing: border-box;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
}

#message {
    margin-top: 20px;
    font-size: 24px;
    color: green;
}