This example displays a map of the United States rendered as purple state outlines on a black background using a geographic projection. The code loads US state boundaries from a TopoJSON file via D3 v4 and topojson-client, then draws them as SVG paths with `d3.geoPath` and a `geoAlbersUsa` projection. State shapes are filled purple with thin gray strokes, positioned within an SVG container sized relative to fixed margins.