This interactive zoomable sunburst diagram visualizes hierarchical data, such as product categories across cities, using a circular layout of nested arcs. Clicking an arc zooms into that subtree, while a central circle returns to the root. Built with D3 v5, it employs `d3.partition` for layout, `d3.arc` for rendering SVG paths, and `d3.interpolate` within `transition.attrTween` for smooth animated updates. Data originates from the `@observablehq/flare` module, fetched via the Observable stdlib’s `require` function.