A node tree visualizes the hierarchical structure of countries, grouped by continent and subregion, with labels sized by depth. The data is loaded from `data.json` and processed with `d3.hierarchy` and `d3.tree`. Each link renders as a horizontal path via `d3.linkHorizontal`, while text labels use D3 selections. The SVG supports zooming through `d3.zoom`, and styling uses a Playfair Display font with white text shadows.