This D3 map visualizes global countries using a natural Earth projection. It renders a blue sphere backdrop with light green country polygons outlined in black. The visualization uses the `d3.geoNaturalEarth1` projection with `d3.geoPath` to generate SVG paths, and the `topojson.feature` API to extract country boundaries from a world-atlas TopoJSON dataset. The map displays a graticule-free, simplified world view with countries filled and stroked according to CSS classes.