PunitDh/self-driving-car-javascript ? reverse-engineered prompt

Build me a browser based self driving car demo in JavaScript where I can watch a little car learn to drive around a simple road on its own.

I want the page to load a clean canvas scene, show one or more cars, and have them avoid obstacles and stay on the road using a basic neural network that is built in the project itself, not pulled in from a library. It should feel like a fun visual experiment where the cars improve over time, and I should be able to see the best brain being reused or saved between runs.

Please make it run directly in the browser with a simple layout and some basic styling, and keep it easy to open and try. If anything about the setup or canvas behavior is unclear, look up current docs online if you need to, then make it work.