#chart_div {
    width: 100%;
    height: 540px;
    background: #ddd;
}

text {
    pointer-events: none;
}

.grandparent text {
    font-weight: bold;
}

rect {
    stroke: #fff;
}

rect.parent,
.grandparent rect {
    stroke-width: 2px;
}

.grandparent rect {
    fill: green;
}

.grandparent:hover rect {
    fill: lightgreen;
}

.children rect.parent,
.grandparent rect {
    cursor: pointer;
}

.children rect.parent {
    fill-opacity: .5;
}