This collapsible tree visualization shows hierarchical data from a JSON file, where nodes can be clicked to expand or collapse their children. The tree layout is computed using the `d3.tree()` layout algorithm with horizontal links drawn via `d3.linkHorizontal()`. The visualization uses D3 v6 and SVG rendering, with smooth animated transitions (250ms or 2500ms with Alt key) applied to node positions and the viewBox. Clicking a node toggles its children and also collapses any other nodes with the same name, with the tree recompiled via `d3.hierarchy()`.