This example demonstrates how to build a map visualization using D3.js, displaying geographic features as green polygons with black outlines on a blue background. It loads GeoJSON data from a remote URL and renders it as SVG paths using the `geoPath` generator with the `geoAiryRaw` projection from d3-geo-projection. The code relies on `d3.json` for data loading and topojson’s `feature` conversion, with all styling defined in external CSS.