line {
  transition: stroke-width 2s;
}

line.link {
  stroke: black;
}

line.active {
  stroke-width: 3;
  transition: stroke-width 0s;
}

.point {
  fill: #555;
}

.fixed .point {
  stroke: #000;
  fill: #ff0080;
  fill-opacity: 1;
}

g.depth-0 {
  z-index: 100;
}
g.depth-1 {
  z-index: 90;
}
g.depth-2 {
  z-index: 80;
}

.depth-0 text {
  font-size: 4em;
}
.depth-1 text {
  font-size: 3em;
}