This treemap visualizes steel scrap exports from partner countries, with each initial rectangle representing a country and its total export value. Clicking a country drills down to show a secondary treemap of that country’s commodity descriptions and their values. Built with D3 v7, the visualization uses `d3.hierarchy` and `d3.treemap` to compute the layout, rendering rectangles and labels as SVG elements. Data is loaded from a CSV file, and the drill-down interaction uses D3 transitions to animate the rectangle sizes and text updates over 500 milliseconds.