This example presents two synchronized SVG maps: a world map colored by 2022 population data and a zoomed view of Portugal. It uses D3 v7 with the `d3.geoNaturalEarth1` projection, `d3.geoPath`, and `d3.geoGraticule` to render country boundaries and graticules from world-atlas TopoJSON. Population values from a CSV drive a sequential blue color scale, and hovering over a country triggers a tooltip showing its name and population.