I have seen these style of lists on other wikias so i know it can be done in wikia as well. I have tried a lot of tutorials, adding stuff to my .css (I think it is called this way), added a lot of templates which I have already deleted again.
So is there anyone who can give me an explanation and the codes to add to make this work?
I just found out why it didn't work. When pressing preview I just got a box with the text that was supposed to be inside the collapsible box but when saved the expand button appears and I can expand my lists ^.^
You are getting the box because of this section in your wiki's CSS. It looks like this is from something else that got copied/adapted from another wiki. Note that other aspect besides the box are also affected.