1.5.5f php 7.1

in navigation menu at top of page when enabled the gap between categories is determined in stylesheet.css this line
Code:
#navCatTabs ul li a {text-decoration: none;padding: 0em 0.5em;margin: 0;color: #2277f7;white-space: nowrap;}
I would like to change [white-space: nowrap;] to be a vertical 'pipe' line [space|space] like this; category a | category b | category c - with the ability to modify color of that pipe.

So looking for some help please for some code.

cheers, Mike