This example shows a full-window smiley face rendered as an SVG, with a yellow circle, two dark eyes, and a black stroke outline, all positioned relative to the center of the viewport. It uses React and ReactDOM to create each SVG circle element, computing coordinates from the window dimensions and drawing the face without a mouth. The stroke is applied with a width of 20 pixels, and the face scales its radius based on the window height minus half the stroke.