area chart
This area chart visualizes yearly data from a CSV file, showing how values change over time. It loads the dataset via `d3.csv` from a GitHub Gist, parses the year and value columns, and renders a filled steelblue area using the `d3.area` generator. The chart uses linear scales for both axes, with an x-axis formatted to show integer years and labeled "Year," while the y-axis is labeled "Value." Axes are drawn using `d3.axisBottom` and `d3.axisLeft` within an SVG container, demonstrating basic data loading, scaling, and shape generation in D3 v7.