Thanks for the quick answer, it took a while, but I'm starting to understand the nesting of classes and elements works. But actually, the problem is that the subItems of the menu don't show up, but if I check the source of the page, they are there, and the styles that I defined in the css are applied. And in the only case that a subsubitem appeared, it was disabled. So I think this is mostly an issue of configuration of control/properties of pages than css, besides, if it were only css, the items should be there, ugly as hell maybe, but there.
I set the "LastExpandLevel" property of the radMenu to more_than_0, and the "Show in navigation" property of certain pages to "Yes", so as far as I understand how it works, the menu should show me all those pages as long the hare in a level no grater than the LastExpandLevel, am I right here?
Previously, there were 2 radMenus in the site, one with the main sections, and the other for each one seting the StartingNodeOffset and StartingNodeUrl for the section I wanted, but I took off that 2nd menu in an attemp to have all the navigation functionality in one place.