A grid of 36 smiley faces renders via React components, with each face composed of D3-generated SVG shapes for the background circle, eyes, and mouth. The faces vary slightly in eye position and radius due to randomized values applied per face. Using `range` from D3 to generate the grid, the app maps each index to a `Face` component, scaling the composition across the viewport. The mouth uses D3’s `arc` generator with a fixed inner radius and angular span, while SVG `g` transforms center each face within its container.