This bar chart shows the average sales for each product line from a GitHub-hosted CSV file, with each bar’s height representing the mean sales in USD. The chart uses D3 v7 to fetch the data via `d3.csv`, compute averages with `d3.rollup` and `d3.mean`, and render SVG bars with scales from `d3.scaleBand` and `d3.scaleLinear`. Interactive tooltips appear on mouseover, displaying the product line and its average sales. Axes and labels are generated using `d3.axisBottom` and `d3.axisLeft`.