This example shows a minimal React-rendered smiley face, with a brown circular head, black stroke outline, and two black eyes positioned symmetrically on a light gray background. The code uses React 16.9.0 and ReactDOM to render SVG elements directly into the DOM, computing dimensions from `window.innerWidth` and `window.innerHeight` so the face fills the viewport. It defines a single `App` component that draws the head as a `circle` with a transform to center it, and two eye circles offset by fixed pixel values. The rendering is purely static SVG, driven entirely by React’s declarative component structure.