A smiling face made from yellow SVG shapes reacts as its eyebrows repeatedly raise and lower. D3.js v5 positions circles for the eyes, rectangles for the brows, and an arc-generated path for the mouth within a grouped coordinate system. Chained `transition().duration()` calls animate the eyebrow group’s transform attribute, cycling its vertical offset to create the expression. No external data is loaded; all geometry is defined through hardcoded constants and D3’s `arc` helper.