.legend {
    margin-bottom: 1rem;
}

.legend div:before {
    content: '';
    display: inline-block;
    width: 1rem;
    height: 1rem;
    vertical-align: middle;
    background-color: gray;
    margin: 0 0.5rem;
    opacity: 0.5;
}

.columns {
    display: flex;
    height: 600px;
    align-items: stretch;
    border: 1px solid #CCC;
    margin-bottom: 10rem;
}

.columns .column {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-end;
    position: relative;
}

.columns .column .bar {
    border-right: 1px solid white;
    font-size: 0.5rem;
    text-align: center;
    position: relative;
    opacity: 0.5;
}

.columns .column::after {
    display: block;
    content: attr(data-value);
    position: absolute;
    top: calc(100% + 1rem);
    writing-mode: vertical-rl;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.columns .column .bar.activated,
.legend div.activated:before  {
    opacity: 1;
}

.columns .column .bar.first,
.legend .first:before {
    background-color: salmon;
}

.columns .column .bar.second,
.legend .second:before {
    background-color: seagreen;
}

.columns .column .bar::after {
    display: block;
    content: attr(data-value);
    color: white;
    position: absolute;
    font-size: 0.75rem;
    line-height: 1rem;
    left: 0rem;
    top: calc(50% - 0.5rem);
    width: 100%;
}