This example renders a full-screen smiley face using React and SVG. The face is centered, with a yellow circle for the head, two black eyes, and a wide mouth, all sized dynamically based on the browser window dimensions. It uses React’s `ReactDOM.render` to mount the component and constructs the SVG elements with JSX, applying transforms for positioning. The code employs React 16.9 and sets stroke widths and radii as variables, though no mouth is drawn in the final output.