This example displays a simple line chart of S&P 500 stock prices over time, using a temporal x-axis and a quantitative y-axis. The visualization loads CSV data from a GitHub gist and renders the line mark directly in the browser. It is built entirely within a single HTML file using the Vega-Lite specification, then embedded into a `<div>` via the `vegaEmbed` function, with Vega and Vega-Lite loaded from a CDN.