This example renders a full-screen smiley face using React and D3’s `arc` generator for the mouth. The face consists of a yellow circle with a black stroke, two black eye circles, and a curved mouth path created via `d3.arc` with specified inner and outer radii, angles, and corner radius. The SVG is sized to the browser window, and all elements are positioned relative to the center using a translated group. The code uses React for component structuring and D3 v7’s `arc` API for path generation.