PHP: Add a loading spinner while the data is retrieved and make it responsive and add validation if data not retrieved and button to export to PDF

Hi, I have a working PHP file that retrieves invoice details from the oracle database based on the parameters provided in the URL. It is working fine, no issues just the following needs to be added to it: (a) A loading spinner while the data from Oracle is being retrieved. (b) Proper error message, if data is not fetched or some error or network issue, etc (c) Make it responsive by adding CSS, the minimum width for the tables is 620 for the PC browser, while opening in mobile, initially, it displays in 620 widths but if you zoom out it is responsive. (d) A button to export to PDF. It is a simple job, maybe takes 1-hour max. Serious people only bid and bid the correct amount, don't bid less amount and negotiate. I am attaching the PHP file itself, have a look into it. I cannot provide a working server, you change the file, send it to me, I upload, test, and provide feedback.