What is this page margin on the right?

I have this margin on the right side of all my pages that I can't get rid of. When I inspect it with the inspect element tool it highlights in a purple color with diagonal dashes but it doesn't tell me what it is. I've tried messing around with margin in the inspect element code.

I also tried troubleshooting all my custom CSS to see if that is causing it.

Any ideas?

(link below)