This visualization pairs a choropleth map with a scatterplot to explore global demographic data from a 2023 CSV and GeoJSON world map. The map uses `d3.geoEqualEarth` and `d3.geoPath` to color countries by birth rate, while a `d3.scaleLinear` maps fertility rate and life expectancy onto the scatterplot axes, with point size encoding population. Both SVGs support synchronized mouseover highlighting that turns matching countries or points red, using `d3.selectAll` with shared ids.