smiley face woohoo
A smiling face rendered as a yellow SVG circle with black outline, two eyes, and an arc-shaped mouth. The React components BackgroundCircle, Eyes, and Mouth compose the face, centered via a group transform. D3’s `d3.arc()` generates the mouth path, while fixed numeric constants define layout. The static example uses React 16.9 and D3 v7, with no interactive data.