This example visualizes trading-day data as a scatterplot, mapping the trading day on the x-axis, trading time on the y-axis, and encoding color by count and circle size by percentage of buy orders, with tooltips showing buy counts. It uses the Vega-Lite API (`vl.markCircle`, `vl.encode`) with D3’s `csv` loader to fetch data from a GitHub-hosted CSV file. The visualization is rendered as SVG via Vega, with custom config for improved readability and a Vega Tooltip handler for interactivity.