Main menu items alignement

Hello,

I have some problem with the main menu in the top header. I have mostly “personalized link” type menu (that i use to point to the “color section” anchor) ; and those items of my menu are not shown on the same line that the other “page” menu items, or language flag.

Why is there such a difference ? What should i do to solve that problem ?

Thank you for your help
Regards

Germain.