A multi-line chart tracks cumulative COVID-19 deaths over time for each country, with a logarithmic y-axis. A Voronoi overlay, built using `d3.Delaunay`, enables hovering anywhere near a line to highlight that country’s series and display a tooltip with the exact death count and date. SVG paths render the lines, with the active line emphasized thicker in black. Data comes from the Johns Hopkins Coronavirus dataset, fetched via `d3.csv`.