Fork of Smiley Face Part II
A yellow smiley face fills the browser window, centered via SVG circles and positioned with a transform on a group element. React calculates the face’s dimensions from `window.innerWidth` and `window.innerHeight`, rendering two fixed eye circles and a yellow head with a black stroke. The code uses React 16.9.0 and ReactDOM to mount the SVG to a root div, with no mouth or interactive behavior beyond the static visual.