This example shows a smiling face rendered as a full-screen SVG, with a yellow-to-red radial gradient filling the head, black stroke outlines, two eyes, a small nose line, and a curved mouth created using a D3 arc generator. The visualization is built with React components react and react-dom, while D3.js provides the `arc` function for mouth geometry and handles the SVG coordinate transformation. The face scales dynamically to the browser window size, using `window.innerWidth` and `window.innerHeight` for centering and radius calculations.