Can someone explain me how installing a lightdm greeter (web-greeter) can completely break gtk+ themes and elementary-tweaks. How is that even related to each other and why does my fucking lock screen still look like crap? Seriously, I spent the whole day trying to fix my desktop environment and now it turns out that removing a lightdm config file fixes gtk themes on my desktop. How on earth is a fucking lightdm config file related to my desktop environment's ability to load gtk+ themes. It doesn't make sense. I should really stop messing around with things...

I cloned the github repository of lightdm web greeter. Then I built it. It didn't work, so I thought it didn't do anything at all. So I tried to install lightdm-greeter-gtk, which did work I think. I kind of forgot what I did after that, but I started to screw up a lot. At some point lightdm was crashing, so I purged it, which installed gdm and other things I don't want. Then I reinstalled lightdm, I also tried reinstalling elementary-desktop and I tried editing gtk3 settings files. But nothing worked. I have also installed gnome tweak tool, which I should not have done. Elementary-tweaks coukdn't change my gtk theme anymore.

I fixed the gtk theme problem by removing /etc/xdg/lightdm/lightdm.conf.d/90-greeter-wrapper.conf and a couple of other files web-greeter created. The icons on my lock screen (pantheon-greeter now again) are still wrong and the clock is of center now though. I'm currently trying to find a file that might cause this in /use/share/glib-2.0/schemas/, but everything seems right, so I'm not really sure why it's messed up.

@FrodoSwaggins Here is my apt log:
https://pastebin.com/3WYanJJS

@FrodoSwaggins I guess I've learned my lesson now: always be careful with display managers. I was also looking for a way to reset lightdm configs, but I couldn't find the answer.

@Frodoswaggins I'm using elementary os, sorry if I'm a little late.

@FrodoSwaggins I could switch to Debian and install Pantheon DE, but that seems pointless, because elementary os is based on Ubuntu which is based on Debian. I just like the way elementary os looks (or should I say: the way it's supposed to look), I don't really want to change to another DE.