A full-screen SVG smiley face is rendered with React, drawing a yellow circle with a black outline and two small eye circles. The code computes dimensions from `window.innerWidth` and `window.innerHeight`, centering the face with a `translate` transformation. It uses ReactJS and ReactDOM to render the SVG elements, with explicit variables for eye offset, eye radius, and stroke width. The face scales to the browser window, featuring a static, non-animated expression.