This example shows a React-generated smiley face rendered as a full-screen SVG. The face consists of a yellow circle with a black outline, two black eye circles, and no mouth, all positioned relative to the viewport’s center. The code uses React 16.9 and ReactDOM to mount an SVG element, with dimensions and offsets computed from `window.innerWidth` and `window.innerHeight`. It utilizes SVG `<circle>` elements and a `<g>` transform to center the composition dynamically.