Fluidity of primary navigation bar

Fluid width on the primary navigation bar throws off balance on very large screens, making it difficult to interact with the elements as they are far from the content. There should be consideration of different screen sizes.

Ex: ux-research#3 (comment 26005470)

I would like to add that I absolutely dislike the fluid navigation bar, I am using a 4K screen and it sucks that the navbar is using the complete width, while the content is actually fixed. Wouldn't it be better to have both fixed?

I understand that this isn't a big deal on smaller screens (probably even on full hd) but on everything bigger it really isn't that great. I'd prefer to have a universal fixed solution like on GitHub.