v155 Apply dif background color to sublists on category sidebox

I have a zc155e and I'm working with a clone of Responsive Classic.

Here is a link:
https://002mc.justmedical.biz/Hardware

In the category sidebox to the left, I'd like to apply a different background color to sub-category lists. For instance:
Hardware->
|_CDROM Drives
|_Graphics Cards
|_Etc etc

I'd like a unique background for the subcats (those that start with "|_").

Currently, this is the code I've added to control the background:
ul.list-links, ol.list-links {background-color:#99ccff;background-color: rgba(153,204,255,0.6);}

I've googled like mad, tried a bunch of variations like this:
ul.list-links > li, ol.list-links > li {background-color:#99ccff;background-color: rgba(153,204,255,0.6);}
ul.list-links > li > ul > li, ol.list-links > li > ul > li {background-color:blue;}

Any suggestions would be deeply appreciated!