It should have worked because I actually tried it locally…try something like -30px
As for menu positioning, I’m actually doing that with my next theme Circumference which will have the top right but also a bottom centered position available. I know some people have moved the menu, but it’s something that should be done carefully because there’s recoding involved. You could also use a menu plugin and create a container below as you had but put the menu code in that container.
