[Solved]-In d3, how do I apply a style to my line chart for both the line and the area under the line?-d3.js

You are treating your single path like it's two separate elements. It's just one element and your area call (and style) is overriding your line call (and style). If you want to style them different, plot a line and an area.

svg.append("path")
 .datum(data)
 .attr("class", "area")
 .attr("d", area);

svg.append("path")
 .datum(data)
 .attr("class", "line")
 .attr("d", line);

Updated fiddle.