.rows {
    display: table;
    margin-top: 2em;
}

.row {
    display: table-row;
}

.key {
    border: 1px solid gray;
    padding: 0.25em;
    margin-right: 0.5em;
    height: 2em;
    display: table-cell;
    font-size: small;
}

.gap-key {
    background-color: gray;
}

.to-key {
    background-color: beige;
}

.switch-key {
    background-color: lime;
}

.contents {
    padding: 1em;
}