This example shows a smiley face composed of a yellow circular head, two eyes, and an arc-shaped mouth, all rendered as SVG elements. The React component `App` defines the face using D3’s `arc()` generator to create the mouth path, while positioning each shape with explicit coordinates and offsets. It uses React 16.9 for component rendering, D3 v5 for the arc calculation, and ReactDOM to mount the SVG into the page, with styling that hides the body margin and overflow.