This 3D scatter plot visualizes insurance charges as a function of age and BMI, with each point colored by the insured person’s region (southeast, southwest, northwest, northeast) using a custom four-color scale. The visualization uses Plotly.js’s `scatter3d` trace type to render markers within an interactive 3D scene. The code loads a CSV of insurance data via `d3.csv` and maps the `region` field to numeric color values, which are then passed to the `marker` object along with a `pl_colorscale`. Each axis is given a distinct pastel background color, while the chart itself is embedded in a simple HTML page with a pink background and styled title.