FlowFalcon/snack-game ? reverse-engineered prompt

Build me a simple browser snake game that runs in one HTML page.

I want a clean game area, a snake that moves with the arrow keys or WASD, food that appears in random spots, and the score to go up every time the snake eats. The game should end if the snake hits the wall or خودش hits itself, and I want an easy way to restart right away. Please make it look decent with basic styling and keep it responsive so it works on desktop and mobile too.

Use plain HTML, CSS, and JavaScript, and keep everything in the existing files if possible. If you need to check anything, look up current docs online first. Make it feel polished enough that someone could open the page and just start playing.