Question Questions ⇒ merging header and footer of main page to phpbb style?

[meis2m]

Hello
how can merging header and footer of main page to phpbb style?

please first look this:
https://www.inveostore.com/community/
how can add footer and header of main page to forum without conflicting in css?

and header and footer for example is in wordpress , and both of them is dynamic