This example shows a smiley face built with React and rendered as an SVG, with a yellow circular head, two black eyes, and a thick mouth arc, all positioned relative to the center of a 960×500 viewport. React components define the SVG elements, while D3’s `arc()` function generates the mouth path using inner and outer radii and start/end angles. The code uses React 16.9 and D3 v5, with the face drawn declaratively through JSX props like `cx`, `cy`, and `r` for circles, and a `path` element for the mouth.