This area chart displays the count of sales for each region, using a smooth, curved line to connect data points across the categorical x-axis. The chart is rendered as an SVG using D3 v5, with scales for the band and linear axes, and includes axis labels and gridlines. It loads sales data from a CSV file and applies D3’s `area` generator with `curveBasis` to create the filled area beneath the line. Sales values are parsed as numbers, and the chart is styled with custom CSS for tick labels, axis colors, and the shaded area fill.