Center logo in header?

I sure wish I could figure out how to center the logo in the header.

It looks like the header is split into two columns (col-md-6) which are 50% each. Can I somehow change the first column to be, say, 80%? I don’t need much room for social media buttons, if that could be reduced or even moved to another place it seems like that would do the trick. Can this be done with the ‘custom css’ part?