This example shows a smiling face built from SVG primitives—a yellow circle with black stroke, two eyes, eyebrows, and an arc-based mouth—centered on a blue background. The eyebrows animate upward and back down using chained `transition().duration()` calls, creating a brief surprised expression. The code uses D3 v5 selections (`d3.select`) and the `d3.arc` shape generator to construct the mouth, with SVG attributes set for positioning and styling. No external data source is used; all elements are hardcoded.