This example shows a yellow smiley face built from SVG shapes, with its eyebrows smoothly sliding upward and then back down in a repeating animation. The code uses D3.js v5 selections to append a circle for the face, separate circles for the eyes, rectangles for the eyebrows, and a path generated with the `d3.arc` function for the mouth. Eyebrow movement is driven by chained `transition().duration()` calls that update the group’s `transform` attribute.