This example displays global COVID-19 death totals over time for multiple countries as log-scale line charts, rendered as SVG in React. A Voronoi overlay, created with `d3.Delaunay.from` and `voronoi.renderCell`, enables mouse hover detection on any data point, highlighting the corresponding country's line and showing a tooltip with the date and death count. A dropdown menu allows selecting a specific country, though the selected line is not visually distinguished in the code. Data comes from the CSSE COVID-19 time series CSV.