This area chart visualizes monthly sales data from a small inline CSV dataset, showing sales values across twelve months from January to December. The visualization uses D3.js v7 with an SVG rendering approach, combining a filled area path with an overlaid line and circular data points. The chart employs `d3.area()` and `d3.line()` with monotone interpolation to smooth the curve, while `d3.axisBottom` and `d3.axisLeft` provide labeled axes. Interactive tooltips appear on mouseover, displaying the month and sales value for each point.