I've 2 horizontal menus, one for categories Menu2 on the left and the other (Menu1) on the right above the right sidebar
I'd like to keep them on the same level.

I tried some CSS but this is not working…

ul.rMenu-hor.rMenu-hRight li {
margin-top: -5px;
}

I'm using WP-3.4.1 and Ata-3.7.8.
Any help will be appreciated. Thanks.

why now make a custom WP menu - you can add pages and categories to the same menu - then just use teh one menu?

Sure that would be more natural
'cause I'm requested to separate categories (w specific colors) aligned left
from a 2 items menu on the right (centered above the sidebar w other colors)…

what is the url?

http://www.r_f_.com/

try this in CSS Inserts

div#menu2 {
    position:  relative;
    top: -23px;
}