This example renders a world map from TopoJSON data using D3 v5 and React, drawing countries as filled paths on an SVG canvas. The visualization uses `geoEqualEarth` for the projection, `geoPath` to generate paths, and `geoGraticule` to display a graticule overlay, with a distinct red sphere background and blue landmasses. Country geometries are loaded from the world-atlas TopoJSON file and converted to GeoJSON via `feature()`. The React component hierarchy separates data loading (`useData`) from the presentational `Marks` component.