The developer mode shows me diff sizes on the right and on the rulers, if I load a site in the local host. E.g. if I drag my screen to 1200px (number at the side), the rules display 1300px.
So the sizes are not consistent. The rulers show the right size because that's how the site behaves according to my media queries. It is not very comfortable to check the size on the rulers, so I'm searching for a solution.
I found this one issue, but 100px difference is more than any scrollbars and it occurs only with my locally hosted pages: Chrome developer tools window dimensions are inconsistent
PS: I use XAMPP
Maybe it is page scale? Push Ctrl + 0.