body {
    font-size: 18px;
}

#solver textarea,
#solver button {
    font-size: 1rem;
}

.board {
    font-size: 2rem;
}

.board table {
    font-family: Arial, sans-serif;
    border-collapse: separate;
    border-spacing: .75rem;
}

.board td {
    border: 1px solid;
    width: 4rem;
    height: 4rem;
    text-align: center;
    vertical-align: middle;
    text-transform: uppercase;
}