Smiley Face Part I
This example shows a simple smiley face composed of modular React components: a yellow background circle, two black eyes, and a curved mouth rendered as an SVG path. The face is generated from explicit geometric parameters like eye offset, eye radius, mouth radius, and stroke width, which are passed through a `Face` component. The code uses React 16.9 for component logic and d3 v6’s `arc()` API to calculate the mouth shape, with all elements drawn in a shared SVG container.