This example demonstrates an animated gradient landscape using D3 version 6 and SVG. It shows a sky backdrop with a radial gradient, a sun that moves vertically, and two layered terrain paths with linear gradients. The gradients transition colors over time using SVG `<animate>` elements, while the sun’s position animates via its `cy` attribute. The code uses D3’s `select` function to render static text, and the visual is purely SVG-based with no external data sources.