Small Lines On Webpage From Unknown Code

Question

On this website, there are lines on the side and top, almost as if they are margins, but I can't find the code that is the cause. What is causing those lines?

Answer 1

It's part of the user agent style sheet. This stylesheet has a default margin value of 8px. You can see this in the inspector:

Answer 2

The background color of the page is #000000 (black) as you can see in assets/main.css. However, there is a white #pageoverview over the black background.