Based on an idea stolen from StartBootstrap.
Features
All original features were preserved:
- off canvas, full height, vertical menu
- responsive design
- IE9+
...and also added:
- expand/collapse buttons
- auto-collapse menu for 'small' screens (when click a link in menu)
- no horizontal scrollbar when the menu is manually expanded
- sticky header
All in pure HTML, CSS, JS (no JQuery dependency).
A remark:
For simplicyty, I've putted together all parts (HTML, CSS, JS) in the index.html file so that you can access them via 'View Source' in live demo.