This fork of the streamgraph template displays multiple ECG data series as stacked, filled areas over time, with a tooltip that appears on hover to identify each stream. Built with React and D3 v5, it uses `d3.stack` with `stackOffsetSilhouette` and `stackOrderInsideOut` to compute the layout, and `d3.area` with `curveBasis` to generate SVG paths. Data is loaded from a CSV gist via `d3-fetch`’s `csv` function. Hovering changes the opacity of non-highlighted streams, while the tooltip text updates to show the active series key.