* {
    font-family: Arial, Helvetica, sans-serif;
}

h1 {
    text-align: center;
}

#board {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    grid-template-rows: repeat(3, 100px);
    grid-gap: 10px;
    justify-content: center;
}

#board div {
    
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 5em;
    border: 1px solid #87cefa;
}

.x {
    color: red;
}

.o {
    color: blue;
}