World Countries Tree
This visualization displays a hierarchical tree of world countries grouped by continent and subregion, using a left-to-right dendrogram layout with horizontal links rendered as SVG paths. Each country appears as a text label, with font size decreasing by depth to emphasize hierarchy. The visualization is built with D3 v5, using `d3.tree`, `d3.hierarchy`, `d3.linkHorizontal`, and `d3.zoom` for pan/zoom interactivity. Data comes from a local JSON file with nested structures. Labels use the Playfair Display font, and the tree is positioned with custom margins against a fixed full-screen SVG canvas.