Right-align a single item in a menu

I have a WP3.1 site with theme Weaver 2.0, url: https://www.musicaljournaal.nl/mj_nieuw (it’s in Dutch, but my question is not content related).

In my top-menu, all menu-items are left-aligned. I want to have the last menu-item (“Login”) aligned to the right of the menu-bar, thus leaving space before that item.

I suspect it can be arranged with the “CSS Class” element in the definition of the menu-item, but I don’t know what to enter. Anyone have a clue, or even better, a solution?