A yellow smiley face with black eyes, outlined by a thick black circle, is drawn in SVG using React and D3 v7. A curved path forms the mouth, which animates its stroke color to red when a button is clicked, using D3’s `transition()` and `attr`. The face is centered on a full-window canvas with dimensions calculated from `window.innerHeight` and `window.innerWidth`, and all shapes are positioned via transforms relative to the center.