A multi-line chart tracks cumulative COVID-19 deaths by country over time using a logarithmic y-scale. The visualization highlights a country's trajectory when hovering over any data point, leveraging a Voronoi overlay via `d3.Delaunay` for efficient nearest-point hit detection. The React app fetches data from the CSSE GitHub repository using `d3.csv`, renders SVG paths with `d3.line`, and uses `d3.axisBottom` and `d3.axisLeft` for axes.