This fork of a D3 tree structure visualizes a dataset on cardiovascular disease, breaking down the root "Heart Disease" node by sex and age category, with leaf nodes displaying related statistics. The chart uses a hierarchical layout created with `d3.tree()` and `d3.hierarchy()` to position nodes, rendered as SVG paths and circles. Node text labels are styled via CSS, while links and node colors are set through inline styles in JavaScript. The source code defines the data structure explicitly, and the visualization updates dynamically based on this nested hierarchy.