This example visualizes global COVID-19 deaths over time as a line chart, with a horizontal marker line at six million deaths and a vertical marker at the most recent date. The chart uses React components wrapping D3 scales and axes, including `scaleTime`, `scaleLinear`, and `axisBottom` for gridlines. Data is loaded from a CSV file and aggregated by day from the CSSE COVID-19 dataset. Rendering uses SVG paths generated by D3's `line` generator.