A smiling face made of yellow SVG shapes animates its eyebrows upward and downward in a loop. Built with D3 v5, the example uses basic selections to append and style a circle, two eye circles, rectangular eyebrows, and an arc-shaped mouth. The `arc` generator creates the mouth path, while chained `transition().duration()` calls animate the eyebrow group’s translate transform over two seconds each way. The SVG is centered via a translated group based on the viewport dimensions.