This example displays the total COVID-19 cases per country as of August 30, 2020, using circles sized by a d3.scaleSqrt on a world map. The map is rendered with d3.geoPath and a geoNaturalEarth1 projection, while country boundaries come from TopoJSON world-atlas data. Hovering highlights countries, and a size legend with a color legend—built via custom legend components—explains the scaling. The visualization supports zooming and panning through d3.zoom, with SVG circles positioned using d3.geoCentroid and the projection.