This zoomable treemap visualizes hierarchical data with interactive drill-down navigation. The chart renders rectangles sized by a primary measure, with a grandparent breadcrumb bar at the top for navigating back through levels. Hovering highlights child rects and displays a custom light-blue tooltip with additional metrics. The implementation uses `d3.hierarchy`, `d3.treemap`, and SVG animations, while the data is preprocessed through `d3.nest` to build the nested structure from flat records.