This example shows a responsive smiley face rendered as a full-screen SVG. The face consists of a yellow circle head with a black stroke, two black eye circles, and is centered using calculated window dimensions. The code uses React with ReactDOM to render the SVG elements, and the component reads `window.innerWidth` and `window.innerHeight` to set the canvas size. A `<g>` transform translates the origin to the center, and circle coordinates are offset from that point to position the eyes.