A grid of 18 small smiley faces, each generated with randomized facial features, fills the viewport. The faces are constructed from SVG primitives—a yellow circle for the head, two smaller circles for the eyes, and an arc path for the mouth. The React components (`BackgroundCircle`, `Eyes`, `Mouth`, `FaceContainer`) compose the face, while the `d3.arc` API sets the mouth’s inner and outer radii and angular range. Random `Math.random` values vary stroke width, eye position, and mouth dimensions for every face.