Fork of Let's make a face with D3.js!
A D3.js animation displays a yellow smiley face whose eyebrows move up and down in a repeating loop. The face is constructed from SVG primitives—circles for the eyes, rectangles for the eyebrows, and a path for the mouth—positioned within a group. The animation uses the `transition` API to smoothly interpolate the eyebrow group's `transform` attribute over two-second intervals between two vertical offsets. The code demonstrates fundamental DOM manipulation, importing `select` and `arc` from the D3 library to build and style the elements.