This example visualizes the Old Faithful dataset as a 2D heatmap, splitting the data into four facet panels based on two repeated row and column fields. Each panel displays binned counts of eruptions, with color intensity representing frequency, using a green color scheme. The visualization is built with Vega-Lite and Vega-Embed, leveraging the `repeat` operator and a `Maxbins` parameter bound to a slider for interactive bin-width control. Data is loaded from a CSV via D3’s `d3.csv`, and the chart renders as SVG with a transparent view stroke.