Changing link color to match with source node color. 

```
    var link = linkG.data(sankeyLinks)
      .enter()
      .append("path")
      .attr("d", curveSankeyForceLink)
      .style("stroke-width", function (d) { return Math.max(1, d.width); })
      .style("stroke", function (d) {return colour(d.depth); })
      .style("opacity", 0.7);
```

This code did not work. Changed red:black to colour(d.depth)