This example demonstrates a clean, modular D3 project structure by rendering a set of colored circles positioned on an SVG canvas. It shows how to separate data loading, visualization logic, and styling into distinct files, with data defined in a JavaScript module and imported alongside D3. Using D3 v7's `select` and `selectAll().data().join()` pattern, the visualization binds circle elements to the imported dataset and applies `cx`, `cy`, `r`, and `fill` attributes. The page is styled with a gradient background and a shadowed SVG container via plain CSS.