A smiley face is rendered across the full browser window using React and D3. The code draws a yellow circle with a black stroke as the head, two black eyes positioned symmetrically, and defines a mouth arc via `d3.arc()` that is not yet appended to the SVG. All shapes are generated as React components within an SVG element, with dimensions computed from `window.innerWidth` and `window.innerHeight`. The example uses React 16.9 and D3 v6, relying on declarative JSX for the visualization.