A yellow smiley face is drawn in an SVG canvas using React components. The face consists of a yellow background circle with a black stroke, two black eyes positioned symmetrically, and a mouth created with a d3 arc path. The code uses React functional components (`BackgroundCircle`, `Eyes`, `Mouth`) and the D3 `arc` API, with all geometry defined by constants. The rendering relies on ReactDOM to mount the SVG into a fixed full-screen container, with no external data source.