If you look at the comments of the HTML file, you will see the following:
When I click the page, a ball appears and drops to the bottom of the window. It bounces around the window. When I scroll the page, content scrolls normally but the ball stays in the window, bouncing around.
This comment and the entire file was written by Copilot with no modifications from me. My original prompt contained an instruction to write the prompt itself as an HTML comment – which will make it easier to track prompt history. Also, I instructed Copilot to write the HTML, CSS, and JavaScript in the same file. Interestingly, neither instruction was written into the output, although the rest of the prompt is exact.
The full prompt was something like this:
Keep the HTML, CSS and Javascript in the same page. When I click the page, a ball appears and drops to the bottom of the window. It bounces around the window. When I scroll the page, content scrolls normally but the ball stays in the window, bouncing around. Write this prompt into the HTML comments.
The exact text of the missing instructions is lost. I forgot to save it when I needed to reboot the computer. My computer has lasted many years but occasionally suffers from age-related performance and storage issues. Since I suffer from the same, I can hardly judge it. It remains my preferred tool for writing.