add space under parent level

1.) I’ve set the font of my highest level parent as larger. Really wanted it to appear as a linkable title- but that wasn’t an option and workarounds didn’t seem to work.  Best option seems to be to “display highest level parent page” within your plugin- but if so, I need to add space and style it beyond the preset options available.  Looking over past requests I found this CSS:

.parent-sidebar-menu > li.current_page_item > a {
border-bottom:1px solid rgba(0,158,222,.2);
}

which put a border under it (but only when highest level is also the current page). How would I do this, but add more space instead of a border? And have the space always appear below the highest level parent, no matter what page was the current page? And at same time, not alter current space between any other levels, only between highest level and rest of side nav?

Just want to increase space between the highest level and rest of submenu and have that space present, regardless of what the current page is.

2) Lastly, I saw in options of Pro version that I should be able to rename a level.  For example one page has a long title. In sidebar, I’d like to not use the actual page name, but a shortened version.  Display page name as? How do I do that?

Thanks in advance