World Countries Tree
This tree visualization displays the hierarchical structure of world countries, organized by continent and subregion down to individual nations. Using D3.js v5 with the `tree` and `hierarchy` layouts, it renders an SVG with horizontal links via `linkHorizontal` and text labels sized by depth. The visualization supports pan and zoom through the `zoom` API, with data loaded from a local JSON file. Text styling uses the Playfair Display font with white shadows for readability against the mint-colored paths.