This interactive visualization displays the historical price of the S&P 500 index over time as a dual area chart, where a smaller overview panel allows the user to brush an interval to zoom into a detailed panel above. It leverages the Vega-Lite and Vega-Embed JavaScript libraries to render the chart, with the data fetched from a remote CSV file hosted on GitHub. The visualization is implemented in a bare HTML page, using the vegaEmbed function to load a Vega-Lite specification from a separate JSON file.