enn.VennDiagram()
                             .width(500)
                             .height(500);

            d3.select("#dropshadow").datum(sets).call(chart);

            var colours = d3.schemeCategory10;
            var areas = d3.selectAll("#dropshadow g")
            areas.select("path")
                .filter(function(d) { return d.sets.length == 1; })
                .style("fill-opacity", .1)
                .style("stroke-width", 5)
                .style("stroke-opacity", .8)
              