A smiley face rendered as an SVG fills the entire browser window, with its circular head, two eyes, and a mouth positioned dynamically relative to the viewport dimensions. The React component uses `window.innerWidth` and `window.innerHeight` to calculate the center coordinates and radius, ensuring the face scales to any screen size. It leverages React’s `createElement` and `ReactDOM.render` to mount the SVG elements, while hardcoded offsets (`eyeOffsetX`, `eyeOffsetY`) and radii (`eyeRadius`, `mouthRadius`) define the facial features. The code relies on React 16.9.0 and standard SVG circle primitives, with no additional data sources.