A yellow smiley face rendered with React and D3 fills the browser viewport, with two solid black eyes and an open mouth created as a D3 arc path. The face scales to the window size, centering the head at the midpoint of the screen. Built with React 16.9 and D3 v6, the visualization computes geometry from window dimensions, using `d3.arc` for the mouth and SVG circles for the eyes and head, with the head’s radius derived from the viewport height. The example uses production builds of React and D3, rendering exclusively with SVG elements.