This example shows how to create the drop shadow effect in a map using Canvas.
Since the Canvas object already has the tools to do that, the code is really simple.
Modified http://d3js.org/d3.v3.min.js to a secure url
Modified http://d3js.org/topojson.v0.min.js to a secure url
https://d3js.org/d3.v3.min.js
https://d3js.org/topojson.v0.min.js