This interactive treemap visualizes steel scrap import and export quantities by partner country for a selected region, with each rectangle sized by trade value and colored on a light-to-dark blue scale. Users filter by region and import/export direction via dropdown and radio buttons, and clicking a country drills down to show commodity-level details. Built with D3 v7, it uses `d3.hierarchy` for data nesting, `d3.scaleSequential` with `interpolateRgb` for color, and SVG elements with `.exit()` and `.enter()` patterns for updates. The tooltip reveals both monetary value and shipment quantity.