This example shows a yellow smiley face rendered responsively to fill the browser window, with its facial features positioned relative to the viewport center. The face is drawn using React components that generate SVG elements, including circles for the head and eyes and a d3.arc() path for the mouth. The code uses React 16.9 for component structure, ReactDOM for mounting, and d3.v7’s arc generator to create the curved smile with specified inner and outer radii and angle ranges.