World Map
A world map visualization renders the countries of the world as filled paths using the `geoEqualEarth` projection and `geoPath` from D3. The map is drawn with SVG, with each country’s boundary stroked in a teal color. The data comes from the world-atlas TopoJSON dataset, which is fetched via `d3.json` and converted to GeoJSON features using the `topojson` library’s `feature` function. The visualization is built within a React application, where the `Marks` component maps each feature to a SVG `<path>`.