This example renders a world map using the equirectangular projection, filling each country solid red against a blue sphere. It highlights countries in black on hover. The visualization loads TopoJSON world-atlas data, converts it to GeoJSON with TopoJSON’s `feature` method, and draws paths using `d3.geoPath` and `d3.geoEquirectangular`. The SVG output is styled via CSS, and interactions rely on the `:hover` selector.