AIBOT0116/exceltotxt ? reverse-engineered prompt

Build me a simple web page that lets someone upload an Excel file and turn it into a plain text file.

I want it to feel easy and clean, with a big upload area, a clear button to convert, and a place to show the text result before downloading it. If the file has more than one sheet, let the user pick the sheet they want. Make it handle common Excel files and show a friendly error if the upload fails or the file is empty.

Keep the design minimal and responsive so it works well on phone and desktop. If it helps, add a separate maintenance page that can be shown when the app is temporarily unavailable.

Please make the experience straightforward for non technical users, and if you need to check anything current about browser file handling or Excel parsing, look up the latest docs online first.