This example demonstrates a simple interactive template built with React and D3 v6, rendering an SVG circle that follows the mouse cursor across a 960×500 canvas. The app uses React’s `useState` and `useCallback` hooks to track and update the mouse position on every `mousemove` event, while the circle’s `cx` and `cy` attributes are bound directly to that state. The template shows how to combine React’s declarative component model with D3’s SVG primitives for real-time user interaction without explicit D3 selections or transitions.