Hello HTML
This example shows a smiling face built from a yellow circle, two eyes, and an arc-based mouth, centered in an SVG canvas. It demonstrates how to combine React components with D3 shape generators, using `d3.arc` to create the mouth path and passing props like `eyeOffsetX` and `eyeR` to reusable components. The rendering relies on React’s declarative JSX structure, with D3 v5 and React 16 loaded via CDN, and the face is positioned using an SVG `<g>` transform.