Smiley Face v1
This example shows a classic yellow smiley face rendered as an SVG, with a circular face, black outline, two eye circles, and a curved mouth arc. The face is centered in a 960 by 500 viewport, with the mouth drawn as an arc using the `d3.arc` API, specifying inner and outer radii and start and end angles. The smiley is built with React, using `ReactDOM.render` to mount the SVG elements, while the face and eye shapes are created as SVG `<circle>` elements with fixed coordinate offsets and radii. The code relies on D3 v6 for the arc path generation, and the rendering is entirely SVG-based, with no external data sources.