A streamgraph-style line chart displays cumulative COVID-19 deaths by country over time, using data from the Johns Hopkins Coronavirus Dataset. A single line represents each country on a log-scaled y-axis. Hovering over any point activates a Voronoi overlay, built with `d3.Delaunay` and `d3.voronoi`, which highlights the nearest data point, illuminates the corresponding country’s entire line, and shows a tooltip with the country name, death total, and date. The visualization is rendered as SVG in React, with axes and scales from D3 v5.