A yellow smiley face fills the browser window, centered and scaled to the viewport’s dimensions. The face is constructed with three SVG circles: a large yellow head with a black stroke, and two smaller black eye circles positioned symmetrically. The React code uses `ReactDOM.render` to draw the SVG directly, computing coordinates from `window.innerWidth` and `window.innerHeight`. The face’s radius adapts to the available vertical space, and the eyes are offset by fixed pixel amounts.