This interactive sunburst chart visualizes hierarchical data from the Observable `@observablehq/flare` dataset. The visualization displays nested segments as arcs, with each ring representing a level in the hierarchy. Clicking any segment zooms into that part of the hierarchy, making it the new root. The code uses the `d3.arc()` generator (with start/end angles and inner/outer radii) to draw paths, and `d3.partition()` to compute the layout. Interactivity relies on `transition.attrTween` (interpolating between arc geometries over 750ms) and `d3.interpolate` to smoothly animate data positions. Color mapping uses `d3.scaleOrdinal()` with a quantized rainbow interpolator, while labels are rotated and positioned via `labelTransform()`. The SVG rendering is driven by D3 v5's selection and join APIs.