A self-contained SVG scene depicts a stylized sunrise and sunset over layered terrain, using only HTML, CSS, and native SVG elements without JavaScript libraries. The code applies animated radial and linear gradients to color the sky and two overlapping landscape paths, while a circle animates its vertical position to simulate the sun descending and rising. The animation repeats indefinitely over 15 seconds, cycling the sky and land gradient stops between aliceblue and steelblue. This example demonstrates fundamental SVG animation techniques through the `<animate>` element and gradient definitions, with no external data or rendering frameworks.