menu needs to shrink and remain up top

[brlcad]

The intention is for the menu to shrink down to a considerably smaller size as the page is scrolled down, but remain at the top of the window view. This is similar to how the menu currently displaying at /wiki/Main_Page stays on top, but it's desirable for the menu to retain roughly the same appearance throughout the scaling.

[inderpreetsingh]

Claiming this!