Thank you @whyI and @Klaas very much for the quick responses.
Added the snippet and everything works perfectly 
Indeed I am using the newest version. Just updated it and like it.
Also i encountered something that i assume to be a bug in the picture zoom-feature.
The zoom itself works just fine, but when i click an zoom it seems like snipping the image out of the actual text. The result is that the image is displayed bigger but also the text shifts upwards. That would be less of a problem for most people, but I usually try to use images (for example graphs) without a backround so they fit nice to both light and dark style.
So currently i cant realy use the zoom-feature, because i then see text all over the image itself.