I'm fighting with this the whole day and I can't seem to get it to have the same value for left-right margins.
Every time I change the value in "Linked margins" it switches to "Different margins" with different left and right values.
And what's even more interesting is that I can set the Linked margins to 100px but can't do the same for 101px or 101.5px (what I need).
I think it might happen because "Gutter width" option is never changing according to the margins I'm trying to setup (unlike Column width).
Screenshot of what happens when I setup 101px on Linked margins (XD switches to different margins by itself):