A line chart tracks cumulative global coronavirus deaths over time, with each country rendered as a thin gray path on a logarithmic y-axis. A Voronoi overlay, built with `d3.Delaunay`, divides the chart into pointer-sensitive cells, so hovering near any line highlights that country’s full trajectory in red and displays a tooltip with its name, death count, and date. The React component uses `useMemo` to cache the Voronoi cells, and data comes from the Johns Hopkins CSSE dataset.