Choropleth Map
A choropleth map colors world countries according to their economic group, using a sequential spectral color scale with a clickable legend. Built with D3 v5, it loads TopoJSON world-atlas data and renders geographic paths via `d3.geoPath` with a natural Earth projection. The map supports zooming through `d3.zoom`, and hover states highlight individual countries. The ordinal color scale maps economy classifications to colors, with the legend generated by a custom reusable component.