This example shows a heatmap of test results for link styling options, with points colored to reveal density patterns across X0 and Y0 coordinates. Built using the Vega-Lite API, it loads CSV data from a GitHub gist via d3.csv, then renders an SVG visualization with configurable axis styling and a tooltip handler from vega-tooltip. The visualization uses a single markPoint layer with opacity to encode overlapping data points, set to fit the window dimensions and customize fonts for readability.