Fork of Smiley Face Part II
A React-based smiley face rendered as a responsive SVG fills the browser window, with the face centered and sized to the viewport. The code constructs the shape using SVG circle elements for the head, eyes, and mouth, with the mouth arc generated via D3’s `arc()` function. Styling includes a yellow fill, black stroke, and fixed offsets for facial features, all computed from the window dimensions.