Vega-Lite API Template testing
This visualization displays the Auto MPG dataset from the UCI Machine Learning Repository, plotting each car as a circle positioned by miles per gallon on the x-axis and country of origin on the y-axis, with color encoding horsepower. Built with the Vega-Lite API, the example demonstrates a programmatic approach to declarative chart construction, where the visualization specification is defined using the `vl` object's methods like `markCircle` and `encode`. The code registers Vega, Vega-Lite, and the API with `vl.register`, loads CSV data via `d3.csv`, and renders an SVG that fits the full window. Custom axis styling and tooltips via `vega-tooltip` enhance readability.