This interactive heatmap visualizes the Old Faithful dataset, showing the relationship between eruption duration and waiting time through binned rectangular cells colored by count on a green scale. Rendered as SVG via Vega-Lite’s `rect` mark, the visualization updates dynamically as the mouse moves across the page, adjusting the maximum number of bins on the x-axis based on cursor position. The code uses Vega-Embed, Vega-Lite’s API, and d3.tsv for data loading, with the view’s legend offset to the left.