Hi you can add a module class suffix, in the module parameters. Call it whatever you like, such as "new-menu". From there, you just put that class name in front of your code, so if you wanted to use the code above for your new menu, you would write:
.new-menu #rt-menu ul.menu li a, .menutop li.root .item, .menu-type-splitmenu .menutop li .item{
color: #000000;}
You use the suffix as a CSS hook and style away. Hope that helps.
The difficult we do immediately, the impossible takes a little longer.