This example renders a full-screen smiley face using React and SVG. The face consists of a yellow circle for the head, two black circles for eyes, and a d3 arc-shaped mouth, all positioned relative to the window dimensions. The code leverages React 16.9 for component rendering, ReactDOM to mount the app, and the d3 `arc` generator to define the mouth’s path. The SVG canvas fills the entire viewport, centering the graphic via a transformation.