If you’re talking about a page header, as in navigation, logo, etc., they’re always at the top so I don’t understand why that would be a problem.

The common practice for sidebars is to be hidden under a certain pixel and have a menu icon show.

Maybe you could show a screenshot of what you’re doing.

Also, in the component library, linked to at the top of the editer, Bubble gives you 6 headers and 4 sidebars you can use out of the box to make things faster. You can always edit them to fit your use case.