I dont understand whats causing this

[Nabond]

Anyone got an idea what could be causing this outside border to happen? I am on contentmanager with latest CSP and Pure (this has been here for 4 months now, even when updating. I have no idea why...). imgur only shows what i mean when you look at the picture on their website, its small on the screenshot but very noticable on a 32inch screen

https://imgur.com/a/8354JO4