move all nav link and collapse and container behaviors to the toggleable class generation area; this way the .navbar-toggleable-* goes on .navbar, easily affecting everything that needs updating for each breakpoint's use

move padding on nav links and brand to be responsive padding, keeping mobile contents aligned better

- drop the table styles, use flex
- remove commented out code
- consolidate styles a bit
- add a huge flex-grow to the nav, making the assumption you want nav to take up most space