Can you attach a screenshot? It's easier to suggest if I can see what you're looking at and what you want to accomplish.
I've added thick columns between each column and shaded certain sections as well using format borders and format shading. Off the top of my head I don't think you can do just one column border and not the others unless there's a way to programatically do just the first column using a function of some sort.
Just started diving back into this, so others might have an obvious answer I don't know of, but I thought any answer sometimes is better than nothing
You might try creating a calculated field that gives you one value for "A" and another value for everything else. For example:
[Dimension] == "A"
It will return True for that value and False for everything else. Then you can make it a higher level header in the table, like this:
That gives you the line separating the single value you want from all others. Then, if you don't want to see True/False in the Header, simply use the drop down menu on the field in the view and un-check Show Header. Now, you've got a line separating the value you want to highlight.
You might also experiment with row banding using the Level slider to further highlight the value you want.
Hope that helps!
Looks like you deleted some of replies?
If you think it's answered, please make one of the answers as correct.
Otherwise, some people still keep investigating.