A yellow smiley face with two black eyes is rendered to fill the browser window using React and SVG. The face is drawn with a large circle for the head, two smaller circles for eyes, and no mouth, with all shapes positioned relative to the window center using computed dimensions. The code uses React’s `createElement` syntax through JSX and renders directly to the DOM via `ReactDOM.render`. The viewport size is captured from `window.innerWidth` and `window.innerHeight`.