This will set the border style of all tables columns to a solid gray line with a width of 1px and collapse the borders so that adjacent cells share borders.
If you have already tried this solution and it didn't work, you can try to troubleshoot the issue by inspecting the generated HTML code and checking if the table border styles are being properly applied. You can also check the Pega logs for any errors or warnings related to the PDF generation process.
Another solution is to use a third-party PDF generation library that supports CSS styles better than Pega's built-in PDF generator. One example is iText, which has a Java library that can be integrated with Pega to generate PDFs with better CSS support.
If none of the above solutions work, you can consider reaching out to Pega support or consulting with a Pega developer for further assistance.