This example shows a yellow smiley face rendered to fill the browser window, with two black eyes and a yellow circular face outlined by a thick black stroke. The face is drawn using React components that generate SVG elements, with sizes and positions calculated from the window dimensions. It uses React 16.9 and ReactDOM to mount the SVG into the DOM, and positions the face using SVG `<g>` transforms. The mouth is not drawn, and all coordinates derive from the viewport size.