A React-based smiley face fills the browser window, rendered as an SVG with a yellow circle for the face, two black eyes, and a smile implied by the circular boundary. The code uses React 16.9 and ReactDOM to manage the component, with dimensions derived from `window.innerWidth` and `window.innerHeight`. All shapes are drawn via SVG circle elements, positioned using a centered translation transform. The example demonstrates a responsive, full-screen visualization with no additional data source or interaction.