This example shows a stacked bar chart of sales quantities by city for a selected customer segment, with a dropdown to switch segments and a checkbox to toggle sorting by total quantity. Built with D3 v5, it uses `d3.stack` to layer the data, `d3.scaleBand` and `d3.scaleLinear` for axes, and ordinal colors. Transitions animate updates via `transition.duration`, while the data comes from a CSV file of sales orders. The visualization is rendered as SVG.