Drop down menu problem

i have a problem with my menu fields. I use a centered menu style and if i select a sub or sub-sub menu entry the target buttons unfold every time on the top line, not right of the selected entry.
Here is my site: https://www.sachsen.schule/~gym-heidenau/web
If you select “Angebot” –> “Fachbereiche” you can see that the top entry “Naturwissenschaften” is on the top line, not right of “Fachbreiche”.
If a have a long list of entrys it is impossible to jump to the target entry. The menu collapse down before.
Can you help me?

Best regards, Patrick