Header (including page number) is placed within printable area of page, allowing collisions
1) Add a vertical frame above the 1st system on a page.
2) Add a text to the vertical frame
The vertical frame covers the header which in my case has the page number in it. The text of the frame is partially obscured by the frame.
Increasing the top gap of the frame does not seem to do anything if the frame is on top of the page.