This example shows a smiley face rendered in SVG whose eyebrows move up and down in a repeating animation. Using D3.js, the code selects SVG elements, binds data to them, and updates their positions in response to a timer-based loop. The eyebrow movement is achieved through direct `selection.attr` calls on the `transform` and `y` attributes, with the animation driven by a `setInterval` function. The visualization is built entirely with plain D3 selections, with styling handled via an external stylesheet.