Accessible / Progressively Enhanced Bootstrap Nav

Adding greater accessiblity to the Bootstrap Navbar with a progressive enhancement approach. Navigation works without javascript.

• Using Modernizr for JS detection
• Using JavaScript to manage role and aria state

Small Screen

• no-js: Use :target to show/hide navigation
• no-js: Expand collapsed items by default

Larger Screens

• no-js : Make subnav items appear on hover instead of click.
• no-js : Visually hide subnav items with absolute positioning instead of display: none; making them reachable for AT users