This visualization displays a choropleth map of Sweden’s counties, rendered as an SVG using React and D3 v5. The map uses the `geoMercator` projection and `geoPath` to draw both county features and interior boundaries from TopoJSON data. County regions are filled in brown with green strokes, while internal borders appear in black. The data comes from a GitHub-hosted TopoJSON file, and the projection is fitted to the viewport using `fitExtent`.