  .style("fill", function(d,i) { return colours[i]; })
                .style("stroke", function(d,i) { return colours[i]; });

            areas.select("text").style("fill", "#444")
                .style("font-family", "Shadows Into Light")
                .style("font-size", "22px");

          var defs = d3.select("#dropshadow svg").append("defs");

          // from http://stackoverflow.com/questions/12277776/how-to-add-drop-shadow-to-d3-js-pie-or-donut-chart
          var filter = defs.append("filter"