NeatSmiley
NeatSmiley renders a classic yellow smiley face centered on an SVG canvas. Built with React and D3, it composes the face from separate components: a stroked circle for the head, two black circles for the eyes, and a D3 arc path for the mouth. The mouth uses `d3.arc()` with specified inner radius, lip thickness, and angular sweeps to create the smile. The SVG output is generated declaratively through React’s JSX, with the graphics’ geometry and positioning computed from fixed layout constants.