Excel 2016 - Random Dark Gridlines in PDF

I've got an Excel 2016 spreadsheet that I am printing using the "Microsoft Print to PDF" option. I want the spreadsheet to show gridlines. Everything works fine except there are four cells in the spreadsheet where the gridlines are significantly darker than is true for all of the other cells. If I uncheck gridlines, all the cells are consistent - no gridlines, borders, or underlines except where I have intentionally placed them.

I guess I could use outline borders on all of the cells to accomplish what I want, but that's a pain. Any solutions?

By the way, the darker gridlines do not appear on the print preview.

I have shown arrows pointing to the 4 erroneous lines. There are some other lines that are darker than the others, but while I prefer all of the gridlines and underlines to be the same darkness, at least lines are supposed to be in those locations. I tried Export, but that actually resulted in more darkened lines. It's really not a big deal that I can't live with, but I find it curious that I cannot make it print the way I would like.

Thanks for getting back.

Thanks for the feedback.

A few comments.

I want gridlines in my pdf file, but I want them to all be consistent -- almost like faded borders.

I've selected the entire print area and selected "No Borders". Doesn't help.

If I de-selected gridlines in the print setup menu and then create the PDF, it prints with no problem. The erroneous lines do not appear.

I use fill color in a few spots (you can see a little bit where I blanked out the numbers). If I eliminate all "fill" color (NOT font color), the PDF is created properly. I did not use any fill color on the 4 cells that have the erroneous lines.

Therefore, to make it print the way I want, I either have to eliminate the gridlines or eliminate the fill colors. Doing either solves the erroneous line problem.

The only erroneous lines are the 4 lines I indicated with arrows.

Nothing fancy used in the spreadsheet. Very basic except for using some fill colors to highlight certain sections of the spreadsheet where I want to draw attention.

I'm kind of an Excel guru, have used it extensively since it first came on the market. This is one of the very few times that I've come across something I could not figure out. I'm thinking it might be some kind of a bug.

Excellent suggestions everyone. The bug is in the Microsoft Print to PDF. Here's how I know.

Prints correctly on paper, whether it's printed in color or black and white.

I have Nitro Pro 11 so instead of choosing Microsoft Print to PDF I chose Nitro Pro from the Excel print choices. Nitro Pro created the PDF file without the erroneous lines. All of the gridlines were darker with Nitro Pro, but none of them stood out as different.

A few extra observations. No, there are no formulas in the problem cells. And yes, I had already tried different formats for the problem cells with no change. In fact I deleted the lines with the problem cells and then re-created that part of the spreadsheet. No difference. These were things I tried before the suggestion to try printing hard copies. By the way, I use Microsoft Print to PDF all of the time creating spreadsheets much more complex. I think the bug occurs when using fill color along with Microsoft Print to PDF since this is a combo I rarely use. Can someone with Excel 2016 test my theory?

Thanks for all of the suggestions.