This area chart displays total sales across product categories, using a steel-blue filled region beneath a line to emphasize the magnitude of sales for each category. The visualization is built with D3.js v7 and rendered as an SVG. It loads CSV data via `d3.csv`, converts the sales strings to numbers, and uses `d3.scaleBand` for the categorical x-axis and `d3.scaleLinear` for the y-axis. The area and line paths are drawn with `d3.area` and `d3.line`, respectively, and axes are labeled using `d3.axisBottom` and `d3.axisLeft`.