Refactor the navigation bar for desktop, tablet, and mobile.

Refactor the navigation bar for desktop, tablet, and mobile.

Specifically, the navigation bar now shrinks in height on scroll
and when on devices smaller than 768px. Additionally, the search
box disappears at the 1280px break point to avoid text wrapping.
A JavaScript file was added (main.js) to apply the "compressed"
class when scrolling, which is what provides the menu shrinking.