A smiling face is rendered as a yellow circle with black outlines, two eyes, and a curved mouth, sized and positioned to fill the browser window. The example uses React components like `Face`, `BackgroundCircle`, and `Eyes` to compose the SVG structure, while the mouth is drawn using D3's `arc` generator with specified inner and outer radii and angles. All shapes are output as SVG elements within a translated group, driven by props for dimensions and offsets.