This example shows a responsive smiley face rendered at the center of the browser window, with its size adapting to the viewport dimensions. The face consists of a yellow circle with a black stroke, two solid black eyes, and uses React and ReactDOM to create SVG elements dynamically. Positions and radii are computed from `window.innerWidth` and `window.innerHeight`, and the entire drawing is grouped inside an SVG `<g>` element with a `translate` transform. The code relies on React 16.9 and renders via `ReactDOM.render`.