Easier fixed/sticky position SCSS

Currently whenever we add a fixed position topbar, we have:

• hardcode height. Content then doesn't wrap on small screens, gets cut off
• manually update top for every fixed/sticky component

Possible ideas:

• Duplicate fixed position element, for the twin add position-static invisible. This means it takes up the same space, but is not visible
• Use content: attr(title) to clone text content. Depends on duplicating content to an attribute, so not guaranteed to look right if there's markup (e.g. buttons)
• Use JS, Store headerHeight and add padding-top to content element