A line chart visualizes customer growth over time using data from the `data.csv` CSV file, loaded with `d3.csv` and parsed into numeric customer values. The chart renders as an SVG using D3 v7, with a `scaleBand` on the x-axis for discrete year categories and a `scaleLinear` on the y-axis for customer counts. It draws the line as a single SVG `path` via `d3.line`, offset by half the band width, with axes generated by `d3.axisBottom` and `d3.axisLeft`. The static example is a fork of a reusable chart pattern, embedding styling via external CSS.