As you can see, switching to the leuven theme makes my org-mode first level headlines bigger than the rest of the text. I don't like that, where can I change this behaviour? Where is the leuven-code that takes care of this modification? Is this even caused by the leuven theme?
The reason why I don't like this feature is that I'm using my own "first level headline" (see Allgemeines). So as an additional feature: How can I make my own Headings bigger instead of the org-mode headlines? (Maybe the answer to the first question will answer this question too.)
P.S.: I don't want to change the leuven theme, because I like the colors!