A yellow smiley face is rendered as a full-screen SVG, centered in the browser window. The face is built from three circles: a large yellow circle with a black stroke for the head, and two smaller black circles for eyes, positioned symmetrically. The code uses React to create and render the SVG elements, computing coordinates and dimensions dynamically from the window's width and height. The project uses React and ReactDOM, with the SVG output generated directly from the JavaScript component.