Burger icon with pseudo-elements, animated nav background with pseudo-element, off-trigger area (outside nav opened) width pseudo-element.
No repaint, no reflow, no JS, but the blur effect may be a little laggy, particulary on mobile devices.
Featured here: http://fribly.com/2015/08/09/pure-css3-off-canvas-menu/
@ahmad_hania > Nice! Did you notice that you can clic out of the menu area to close it? (not seen in the gif) — Done with pseudo element :)
Yes, I noticed but I didn't add the gif. You can contact them to show it or mention it. Nice work by the way :)
Need to know how to enable it? Go here.