D3 v5 Circle-Packing
This visualization shows a hierarchical dataset as nested circles, with each circle’s size encoding a numeric value and its color representing depth in the tree. Built with D3 v5 and rendered as SVG, it uses `d3.stratify` to convert the tabular flare.csv data into a hierarchy, `d3.pack` for layout, and `d3.scaleSequential` with `d3.interpolateMagma` for coloring. Hovering highlights a node and its ancestors via the `mouseover` and `mouseout` events.