This example shows a responsive smiley face rendered as an SVG, with a yellow circular head, two black eyes, and a curved mouth. The visualization adapts to the browser window size by computing its dimensions from `window.innerWidth` and `window.innerHeight`. The code uses React to create the SVG elements and calls `d3.arc()` from D3 v6 to generate the mouth path. The face is centered using an SVG `<g>` transform, and all shapes are positioned relative to that center point.