body {
    font-family: Arial, sans-serif;
    background-color: #f2f2f2;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

h1 {
    margin-bottom: 10px;
}

#message {
    font-size: 20px;
    margin: 15px 0;
    height: 24px;
}

.board {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    grid-gap: 5px;
    margin: 0 auto;
}

.cell {
    width: 100px;
    height: 100px;
    background-color: #fff;
    border: 2px solid #444;
    font-size: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    user-select: none;
    transition: background-color 0.2s;
}

.cell:hover {
    background-color: #e8e8e8;
}

#restart {
    margin-top: 20px;
    padding: 8px 16px;
    font-size: 16px;
    cursor: pointer;
}