This example visualizes a hierarchical dataset using D3’s pack layout, rendering circles for nodes and text labels for leaf values. The code builds a tree from an inline JavaScript object, sums leaf values with `root.sum()`, and applies a `d3.pack()` layout with a 300×300 size and 10-pixel padding. Each descendant is drawn as an `indianred` circle with white strokes and centered text, positioned via `transform` attributes. The SVG canvas is 960×500 units, and styling comes from an external CSS file.