This example shows five circles positioned on a responsive full-screen SVG, with data loaded from a CSV file containing id and x/y coordinates. Clicking a circle toggles its fill from black to white, adding a black outline to indicate selection. The React app uses a custom hook with ResizeObserver to track container dimensions, then passes d3-selection and d3-scaleLinear to render circles with scaled positions. D3’s csv function parses the data, and the circle selection is managed through React state, triggering re-renders via useEffect.