A smiley face rendered as a responsive SVG fills the browser window, with a yellow head, two black eyes, and a mouth implied by the remaining space. The face scales to the viewport using React to compute dimensions from `window.innerWidth` and `window.innerHeight`, then draws circles with SVG elements. React 16.9 handles the component structure, while the rendering relies solely on native SVG circle tags without additional libraries. The head’s radius and stroke width adjust dynamically to keep the face centered and proportional as the window resizes.