This example renders a large yellow smiley face that fills the browser window using React and D3. The face is drawn with SVG circles for the head and eyes, while the mouth is created using the `d3.arc` generator with inner and outer radii and specified start and end angles. The React component computes dimensions from `window.innerWidth` and `window.innerHeight`, centering the graphic. The code uses React 16.9 and D3 v7, with all elements positioned within a single `<g>` transform.