This example displays a world map using the Mercator projection, with country boundaries rendered as white shapes against a blue ocean background. The visualization loads geographic data from a GitHub gist and uses D3 v5’s `geoMercator` and `geoPath` functions to project and draw the countries. TopoJSON’s `feature` method converts the source data into GeoJSON for rendering. The map is centered and scaled within an SVG element, with countries stroked in black for clear separation.