Smiley face
This example renders a classic smiley face entirely with SVG primitives. The face is built using a yellow circle for the head, two smaller circles for the eyes, and a D3 arc path for the mouth, all grouped and centered via a transform. The code leverages React for component structure and rendering, while importing the `arc` function from d3.js to generate the curved mouth geometry. Stroke widths and positioning are defined through explicit constants, producing a simple, static illustration.