Create a single-file HTML/CSS/JSanimation of a 4-stroke piston engine in cross-section

AI Animation Battle: Clouds ☁️ Which AI did it best? Prompt: Create a single-file with HTML/CSS/vanilla JS only (no libraries/assets) that renders simple clouds drifting across a sky inside a centered square scene container (responsive). Include: slow horizontal cloud movement, soft cloud shapes, light blue sky gradient, and seamless looping. Add a Start button below the square that starts the animation when clicked. The whole animation needs to be 30 seconds and seamlessly loop.