This example displays a hierarchical tree visualization of world countries, with nodes arranged from a central root and connected by curved horizontal links. The text labels scale in size according to their depth in the hierarchy, and the entire diagram supports zooming and panning. Built with D3 v5, it uses the `tree` layout, `linkHorizontal` for path generation, and the `zoom` behavior, with data loaded from a JSON file and rendered as SVG elements styled with custom CSS.