Adding stripes to a page

Is there a way to add a stripe only at the center of a page?

See in page’s formatting. You can have for instance

Stripe 1 for your header
Stripe 2 with an empty background
Stripe 3 your stripe in the middle of the page.

Also, if you need to have a stripe only for the central page area, you can simply use a shape or a floating group, that works as well.