This example visualizes a basemap of Chinese cities, using a Mercator projection centered on China to render province and city boundaries as SVG paths. The map displays the geographic outlines in a muted blue with subtle black strokes. The code uses `d3.geoMercator`, `d3.geoPath`, and TopoJSON's `feature` method to convert TopoJSON data into GeoJSON for rendering. The basemap data is loaded remotely from a GitHub gist, and each feature is styled via a CSS class.