This example shows a direct comparison of monthly car sales between Toyota and Ford as two layered area charts. The visualization uses D3 v6 to load CSV data from a GitHub gist, transform the monthly sales figures, and render smooth areas with the `area()` generator and `curveBasis` interpolation. Scales are defined with `scalePoint` for months and `scaleLinear` for sales values, with axes and a legend appended to the SVG. Both areas are filled in distinct colors with partial opacity to show overlap between the two brands.