This interactive choropleth map colors countries by economic classification using a categorical color scale and topojson data from the World Atlas. Users click the color legend to filter the map, which dims non-matching countries and highlights the selected category via the `onClick` handler. Pan and zoom are enabled with `d3.zoom` and `d3.geoNaturalEarth1` projection for the SVG paths. The legend and map communicate through a shared `selectedColorValue` state, with opacity transitions driven by the color scale.