Some React Stuff
A React application renders a yellow circle with a black border that tracks the user's mouse movement. The visualization uses ReactDOM to mount a `Face` component, which is composed of a `BackgroundCircle` SVG element, alongside eye and mouth shapes with configurable offsets and radii. The code imports React 17 and D3 7 from CDN, with the circle's position and dimensions controlled by props such as `centerX`, `centerY`, and `strokeWidth`. The interactive behavior responds to cursor position within a 960 by 500 pixel viewport.