A yellow smiley face is drawn across the full browser window using React components and D3’s `arc` generator for the mouth. The face consists of a large yellow circle with a black stroke, two solid black eye circles, and a curved mouth path created by `arc()` with specified inner and outer radii and angular extents. All shapes are rendered as SVG elements, with positions computed from `window.innerWidth` and `window.innerHeight`. The code imports `arc` from `d3` and uses React’s `ReactDOM.render` to mount the SVG to the root element.