This example uses D3.js to compose a simple SVG scene with circles, rectangles, and paths, mixing raw shapes with grouped elements. It demonstrates styling via CSS classes, including black strokes on lines and paths with rounded joins. The code appends a circle to an existing SVG using D3’s `select` and `append` methods, while the HTML markup defines the initial geometry and coordinates. Rendering relies on the SVG DOM, with a minimal React setup noted in the README.