d3/examples/cartogram/cartogram.css

#chart {
  width: 960px;
  height: 500px;
}

.black path {
  fill: none;
  stroke: #ccc;
  stroke-width: 3px;
}

.white path {
  fill: #fff;
  stroke: #fff;
}

.grey path {
  fill: #ccc;
  stroke: #666;
}