This example demonstrates a minimal React + D3 visualization scaffold, showing an empty SVG canvas with a gray outer rectangle and light gray inner rectangle to visualize the margin convention. The code uses React 16.13.1, ReactDOM, and d3.v6 loaded via CDN, with a reusable `VizContainer` component that abstracts SVG/group elements and follows the margin pattern. Rendering uses SVG elements created in JSX, with margins displayed via a `showMargins` prop that can be removed for production use.