Modify width of navigation menu

How do I resize my navigation menu? All my menu items are too close to each other

Without a url or a picture, it's almost impossible to say what it might be...
but have you changed this settings!!!
(default is 12 here)

Settings/Advanced Settings -> Other

The number of tabs shown in the navigation menu before the More link for logged in members.: 12
The number of tabs shown in the navigation menu before the More link for visitors.: 12