White margins

Hi, I had hoped that I didn't have to post this as I thought I’d be able to quickly find a solution, but it seems this is a problem only I’ve had and no matter what I do this hasn’t budged. I want to remove the two white lines which are about 3-4 pixels thick that appear next to panes in my explorer but I’m not sure how. I thoroughly checked that nothing was coloured white to cause this happening. Apologies if the photos a bit off btw I can send them again if needed, im new to this and I just wrote this quickly on my phone. Thanks in advance