Header not sticky when scrolling

[3210jr]

Is your feature request related to a problem? Please describe.
When scrolling to the bottom of the page, a user has to scroll all the way back up in order to access the header bar.

Describe the solution you'd like
The header bar can be found: https://github.com/Elsa-Health/ohap/blob/main/app/components/header.imba and should be made to stick to the top of the page when scrolling down.