Wie können CPTs in ein Front-End-Menü eingefügt werden ohne das das Design des Menüs (Main-Menu) zerschossen wird?
Hey awel!
The easiest way would be to create a custom menu in Dashboard > Appearance > Menus. You can easily add your custom post types to it that way.
Other than that it would take a lot of PHP editing. To make it easier you could try this plugin out, https://wordpress.org/plugins/custom-post-type-auto-menu/.
Best regards,
Elliott