This D3 v5 zoomable sunburst visualizes hierarchical data from the Observable @observablehq/flare dataset. Users click arcs to zoom into a category, triggering animated transitions that recompute arc angles and radii via `d3.partition` and `d3.hierarchy`. The code uses `d3.arc`, `d3.scaleOrdinal`, and `d3.interpolateRainbow` for coloring, with SVG paths and text labels rendering the radial layout. `transition.attrTween` animates the shape and position of arcs and labels over 750 milliseconds, while `d3.format` displays numeric values.