Concerning "line widths", there is a request in the wish list -- with focus on the grid lines.
The Idea: to get a better separation between different levels of hierarchy. optimized graphics settings for hierarchical X categories - 2 options
hogi_1-1710596395744.png
... you could add a comment and request a similar setting for the frame.
Workarounds at the moment:
- use reference lines; fortunately, they allow different line widths.
very nasty: if the scale changes, you have to shift the pseudo frame lines.
hogi_0-1710596273365.png
- instead of adjusting the width, adjust the color (via preferences):
hogi_4-1710596757582.png