A tree diagram renders hierarchical data as a horizontal layout of curved links, with the root on the left and leaf nodes extending rightward. The visualization loads JSON data via `d3.json` and computes the layout using `d3.tree` and `d3.hierarchy`, then draws each link with `d3.linkHorizontal` positioned through the tree’s x- and y-coordinates. All elements are rendered as SVG paths scaled to the full viewport, with the body fixed to prevent scrolling.