This is a React and D3 starter template showing an empty SVG visualization area with visible margin guides. It demonstrates the margin convention pattern, where a `VizContainer` React component abstracts the SVG and group elements, rendering gray outer and inner rectangles to display the layout boundaries. The code uses React 16 and D3 v6 loaded via CDN, with the `showMargins` prop controlling visibility of the margin indicators. The example provides a reusable foundation for building custom charts with React components and D3's data manipulation capabilities.