This line chart tracks global cumulative COVID-19 deaths over time, using data from the CSSE at Johns Hopkins. It plots a bold black line and overlays a horizontal marker at the 1,000,000 death threshold, plus a vertical marker at the latest date labeled “now.” Built with React and D3 v7, it uses `scaleTime`, `scaleLinear`, and the `line` generator, rendering as SVG. The `YMarkerLine` and `XMarkerLine` components draw the reference lines and labels.