This example shows an interactive world map that displays country borders and names, with a dark blue ocean sphere and light green landmasses. The map uses the Natural Earth projection via `d3.geoNaturalEarth1` and renders geographic features as SVG paths generated by `d3.geoPath`. Hovering over a country changes its fill to red, and a `zoom` behavior applies pan and zoom transforms to the map group. Country data comes from the world-atlas TopoJSON file, converted with `topojson.feature`.