This example shows a tree diagram where nodes can have multiple parents, linking shared concepts like "Supply and demand" across different top-level categories. The visualization uses D3 v5 and Underscore.js to deduplicate hierarchical data by node ID, then manually recalculates node positions before rendering horizontal links and labels as SVG elements. Clicking a node collapses or expands its children with animated transitions, while zoom and pan are enabled through D3’s zoom behavior. The data comes from a static JSON file, and the code applies a Playfair Display font to the text labels.