This example shows a simple, animated smiley face built entirely with D3.js, where the eyebrows move up and down. It demonstrates fundamental DOM manipulation by selecting an SVG element and using D3’s data join and transition methods to update attributes over time. The code uses `d3.select` and `d3.transition` to animate the eyebrows, while the face itself is drawn with basic SVG shapes. The rendering is SVG-based within a 960×500 viewport, with styles defined in a separate CSS file. No external data source is used; the entire visual is generated programmatically.