This example shows a smiling face built with SVG shapes and animated with D3 transitions. A red background frames a yellow circle with a black stroke, while two small circles form the eyes and an arc path creates the mouth. The eyebrows are rectangles that move up and down using chained `transition()` calls with 500-millisecond durations. The code selects the SVG element with `d3.select`, sets its dimensions and background, and uses `d3.arc()` to generate the smile path, all within a React-compatible setup using D3 v6.