Looks like it adds the margin to the wrong CSS rule in menu.css when i add it via CSS Menu W.
Will create a test menu see if i get the same problem with that.
-- Uppdate! --
When i add the 10 margin via CSS Menu W it adds in the CSS-file: margin: 0 10 0 0; and that aint working, looks like the "px" are stripped away or sum.
//Morgan