This example displays a natural Earth projection world map with semi-transparent teal circles overlaid on each country, sized by 2018 population data from the UN. Country boundaries are drawn using `d3.geoPath` and TopoJSON, while missing population values appear as pink regions. A `d3.scaleSqrt` maps population to circle radius, and a custom legend shows the scale. The map supports pan and zoom via `d3.zoom`, with circle positioning computed from `d3.geoCentroid` and projected coordinates.