This example renders a smiley face as an SVG composition built with React and D3.js. A radial gradient, defined in the SVG `<defs>` element, colors the main circle yellow with an orange rim, while smaller white circles with black pupils form the eyes. The orange mouth is drawn using a path with a computed `d` attribute from the `mouthArc()` function. All shapes are grouped and translated to the canvas center, and the React app is mounted into the `#root` div within a minimal HTML page.