This example uses the Vega-Lite API to render a bar chart of student performance data, showing chapters on the x-axis and total scores on the y-axis, with bars colored by difficulty level and tooltips revealing the total score. The underlying data is a small set of chapter names, percentages, scores, levels, and elapsed times. The visualization is built with the `vega-lite-api` library, which generates a Vega-Lite specification that is rendered by the Vega engine. The code registers both Vega and Vega-Lite, applies custom configuration for axis styling, and uses the d3 `csv` function to fetch data from a remote URL, though the live render uses hardcoded data instead.