A smiling face made of SVG shapes uses D3 v5 to animate its eyebrows in a looping motion. The yellow circle head, black-outlined eyes, and arc-based mouth are drawn with D3 selections and the `d3.arc` path generator. Eyebrow rectangles transition vertically via chained `transition().duration()` calls, moving up and down repeatedly. The static SVG is centered using a group transform, and the animation runs automatically on page load.