Zoomable Circle Packing
This interactive visualization uses a zoomable circle packing layout to display the hierarchical structure of the Flare data set. Each circle represents a node, with nested circles showing child categories, and clicking a circle zooms to that level while clicking the background returns to the root. Built with D3 v3, it uses `d3.layout.pack` for the layout, `d3.scale.linear` for coordinate scaling, and animated transitions via `transition.attr` to smoothly resize and reposition circles and labels. The SVG output uses color gradients based on depth and hover effects to highlight nodes.