#voronoi {
  height: 100%;
  width: 100%;
  z-index: -1;
  position: absolute;
  pointer-events:all;
}
.links {
      stroke: #fff;
      stroke-opacity: 0.9;
    }
.polygons {
  fill: lightgrey;
  opacity: .6;
  stroke: white;
}

.polygons :first-child  {
    fill: none;
    opacity: 0;
}

.sites {
  fill: #fff;
  stroke: #fff;
}

.sites :first-child {
  fill: #fff;
}
.back{
    z-index: -1;
    position: absolute;
}