The problem is resolved.
Had some non-related problems when setting up my SSL certificate.
When these problems where fixed, this problem was gone.
So hooray, I guess?
@sarpreets I have cleared my cache, reloaded my css and the problem also occurs in another browser.
The weird thing is that it only occurs on the subpages and not the mainpage.
It is as if all placed elements have lost their styling and reverted to the standard settings.
A screenshot of both version to visualize the problem better.
View post on imgur.com
@eytchh is it on the whole of your website or just your mainpage?
