A yellow smiley face spans the full browser window, rendered with React components that generate SVG circles and a D3-generated mouth path. The face is built from separate SVG elements: a large yellow circle with a black stroke, two eyes with white highlights, and a mouth drawn using d3.arc with inner and outer radii for thickness. The layout positions all features relative to the viewport center. The example uses React 16.9 for component structure and d3.v7 for the arc shape, with no external data source.