This example displays a world map colored by per-country values from a small CSV dataset, using a blue sequential color scale to encode the data. It loads GeoJSON country boundaries from the world-atlas TopoJSON dataset and renders them as SVG paths with a Mercator projection (d3.geoMercator). The visualization relies on d3.json for fetching, topojson.feature for conversion, and d3.geoPath to generate the map shapes.