.letter {
    display: inline-block;
    width: 32px;
    height: 32px;
    border: 1px solid black;
    font-weight: bold;
    font-size: 1.25rem;
    text-align: center;
    border-radius: 4px;
    margin: 2px;
}
.letter-active {
    background-image: radial-gradient(white 0%, rgba(0,0,0,.25) 90%);
    color: black;
}
.no-border {
    border: none;
}