.board {
    display: grid;
    /* height: 100vh; */
    background-color: black;
    grid-template-columns: repeat(3, 120px);
    grid-template-rows: repeat(3, 120px);
    justify-content: center;
}

.cell {
    display: flex;
    border: 2px solid black;
    justify-content: center;
    align-items: center;
    background-color: white;
    margin: 0px;
    border-radius: 2em solid black;
    font-size: 5em;
}

body {
    background: white;
    display: flex;
    justify-content: center;
    align-items: center;
}

@media (width < 500px) {
    .board {
        grid-template-columns: repeat(3, 80px);
        grid-template-rows: repeat(3, 80px);
    }

    .cell {
        font-size: 1.8em;
    }
}