This example renders a static smiley face using React and D3, drawing a single black circle with a dashed, dark-gray stroke onto an SVG canvas. The React component `App` computes the face’s dimensions—center coordinates, radius, and stroke width—and passes the radius to the `BackgroundCircle` child, which uses D3’s `arc` import (though only a plain `circle` element is output). The visualization is built with `d3.v5` and React 16.9, and the SVG is centered at 960 by 500 pixels, with the circle scaled vertically to create an elliptical face. No interactive or animated behavior is present.