Make full size nav breakpoint max of 960px

[chrisdel101]

In #1590 I noted this issue.

Having the nav bar squish at this large breakpoint makes it both:

• Annoying to use on a laptop, where the screen size is often set to around 850px (864px for me). User always has to manually open the nav to use it.
• Makes it way harder to do development on laptop since full nav and dev tools do not fit on the screen together.

Breakpoint to full nav should kick in between 768-850px like before. Since the links do not fit at these sizes, was reason this change was made, fix needs to implement some solution to hide certain links (or something) to make this work.

[bjohansebas]

Links should not be hidden directly; the option to continue viewing those links should be added through a button. One idea is how GitHub handles it: