A smiling face rendered as a yellow circle with black outline, two eyes, and a curved mouth fills the browser window. The React component generates an SVG using D3’s `arc` generator to create the mouth path, with circle elements for the face and eyes. All dimensions are computed from the window’s width and height, and the SVG scales to the full viewport. The code relies on React 18 and D3 v7, with no external data source; the face is purely programmatic.