Product main navigation no showing

Hi there
My problem is the following
i have a main menu in all my pages (the same main menu)
and this menu dissapears when yo scroll down the page and appears when you scroll up
and when you get to the top it should be static on top of the page till you scroll down the page again
In all pages works perfectly except in the individual product pages, when it gets to the top of the page it doesn′t appears and fixed to the top of the page like the others
I have looked into the inspector and I see no diferences between the pages, the are using the same clases and everything
I have been throught this trouble for 2 weeks

Thank you

The page I need help with: [log in to see the link]