/* Container around the Sudoku puzzle */
#sudoku-container {
    max-width: 400px;
    margin: 20px auto;
    text-align: center;
    font-family: Arial, sans-serif;
}

/* The overall grid container just stacks .sudoku-row blocks */
#sudoku-grid {
    /* Remove the background-color and gap from previous code */
    margin: 0 auto;
}

/* Each row is displayed as a horizontal flex container of 9 cells */
.sudoku-row {
    display: flex;
}

/* Base cell style */
.sudoku-cell {
    width: 40px;
    height: 40px;
    background-color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    border: 1px solid #ddd; /* Default thin border around every cell */
}

/* --- Thick borders for the 3x3 blocks --- */

/* 1) Thick top border on the first row */
.sudoku-row:nth-child(1) .sudoku-cell {
    border-top: 2px solid #000;
}

/* 2) Thick bottom border on every 3rd row (3, 6, 9) */
.sudoku-row:nth-child(3n) .sudoku-cell {
    border-bottom: 2px solid #000;
}

/* 3) Thick left border on the first column in each row */
.sudoku-cell:nth-child(1) {
    border-left: 2px solid #000;
}

/* 4) Thick right border on every 3rd column (3, 6, 9) */
.sudoku-cell:nth-child(3n) {
    border-right: 2px solid #000;
}

/* Input field styling */
.sudoku-cell input {
    width: 100%;
    height: 100%;
    text-align: center;
    font-size: 18px;
    border: none;
    outline: none;
    background: transparent;
}

/* Buttons container */
.sudoku-controls {
    margin-top: 10px;
}

/* Buttons styling */
button {
    padding: 10px 20px;
    font-size: 16px;
    margin: 5px;
    background-color: #126724;
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

button:hover {
    background-color: #005177;
}
