This example shows a simple smiling face built from SVG shapes: a yellow circle for the head, two black circles for eyes, and a black arc for the mouth. The code uses D3 v7 selections and the `arc` generator from `d3-shape` to draw the mouth path, while CSS sets the page margin and hides overflow. All shapes are positioned relative to a centered `g` group, with explicit attributes for radius, spacing, and angles.