Hover effect and border styles not working

For some reason, the hover effects and border styles don’t work on my website any longer. The pictures are still showing, but without any effects. You’re still able to click on the pictures though. Also, the Owl Carousel isn’t working either, but just showing the pictures like a regular gallery. I have tried to deactivate all the plugins, but it doesn’t seem to fix the problem.

Do you have any idea what the issue is?

You can look at my website here:

I’m using:
Wordpress 4.0
FooGallery Version 1.1.8.2

https://wordpress.org/plugins/foogallery/