Limit Hight of Sidebar, Add scrolling

I am using PlusKit @import to display a long list of linked labels. It is displaying the links but it is one long list . I would like the sidebar hight to be limited to the size of one page and have a scroll bar to allow viewing the long list.
This is the code I put into the sidebar page of the of the Inspector.

@import((Alpha File C))

{max-height:100%; min-height:500px} nav ul{height:200px; width:18%;} nav ul{overflow:hidden; overflow-y:scroll;}

I am running
Catalina v 10.15
RW v 8.4.1 (20817)
Stacks v 4.03
Wilderness Theme

I would appreciate suggestions and thank you for your time.

Sorry, too long and was cropped, here’s some code I tried

@import((Alpha File C))

{max-height:100%; min-height:500px} nav ul{height:200px; width:18%;} nav ul{overflow:hidden; overflow-y:scroll;}

Paging @willwood

Not enough information and no link, so I’m going to stay out of this discussion, for now.

The CSS code looks incomplete in both posts, i.e. the first code block has no selector names and the min / max heights are conflicting values. Bit of a code spaghetti going on there.

It’s very easy to give a page element fixed height and force the display of a scroll bar on overflowing content. But in the current context, regretfully I have almost nothing to work with here.