Fork of Fork of Let's make a face with D3.js!
A yellow face with black-outlined eyes and brows animates its eyebrows upward and back downward over four seconds. The figure is drawn with D3 selections, using SVG `circle` elements for the face and eyes, `rect` elements for the brows, and a `path` generated by the `d3.arc()` helper for the mouth. The brow motion relies on chained `transition.attr` calls targeting a transformed group, all rendered in a single SVG canvas.