Two-tier responsive navigation with mobile menu

This implements a two-tier navigation pattern with Tailwind CSS. It has a logo and primary nav links on top, and a mobile menu trigger that reveals a fullscreen modal on small screens. The primary links use Flexbox to distribute them across the top. The modal mobile menu uses DivideY and FlowRoot to style the menu items vertically. Overall this provides a clean, responsive navigation that works on any screen size.