How to control gap between logo and main menu?

I have searched the forums but not found any solution to this issue: how to get control of the gap between the logo and the main menu when placed on the same line? I want the menu, now floating right, to be aligned left with a fixed gap to the logo. On a staging site I managed to place the menu in the wanted position by diminishing the main container from 1200 px to 1140 px, but if one menu object has to be deleted the gap between logo and menu increases.