body {
    font-family: Arial, sans-serif;
    text-align: center;
    margin: 0;
    padding: 0;
    background-color: #f7f7f7;
}

h1 {
    margin: 20px 0;
    font-size: 28px;
}

#game-status {
    margin: 10px 0;
    font-size: 20px;
    color: #333;
}

#board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 5px;
    justify-content: center;
    align-items: center;
    margin: 20px auto;
    max-width: 90vw;
}

.small-board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 3px;
    background-color: #fff;
    border: 2px solid #333;
    width: 30vw;
    aspect-ratio: 1 / 1;
    box-sizing: border-box;
    position: relative;
}

.small-board.highlight {
    border-color: green;
    box-shadow: 0 0 10px green;
}

.cell {
    width: 100%;
    height: 100%;
    font-size: 5vw;
    font-weight: bold;
    text-align: center;
    border: 1px solid #ccc;
    cursor: pointer;
    box-sizing: border-box;
    display: flex;
    justify-content: center;
    align-items: center;
    line-height: 1;
    min-width: 30px;
    min-height: 30px;
}

.cell.disabled {
    cursor: not-allowed;
    background-color: #ddd;
}

.cell.X {
    color: #ff6347;
}

.cell.O {
    color: #4682b4;
}

.winner-block {
    font-size: 6vw;
    font-weight: bold;
    color: #333;
    text-align: center;
    line-height: 200px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    justify-content: center;
    align-items: center;
}

#restart-button {
    margin-top: 20px;
    padding: 15px 30px;
    font-size: 18px;
    cursor: pointer;
    border: none;
    background-color: #333;
    color: #fff;
    border-radius: 5px;
}

/* Mobile responsiveness */
@media (max-width: 600px) {
    #board {
        max-width: 95vw;
        gap: 3px;
    }

    .small-board {
        width: 28vw;
    }

    .cell {
        font-size: 6vw;
    }

    #restart-button {
        font-size: 16px;
        padding: 12px 25px;
    }
}