body:not(.global-nav-is-open) .global-navigation {
  display: none; 			// Hide the global navigation when the .global-nav-is-open class is not present on the body
}
body:not(.global-nav-is-open) #itrp-backdrop {
  display: none; 			// Hide the backdrop
}
body.global-nav-is-open .global-navigation {
  background: white;		// white background color
  display: block; 			// Show the menu
  position: fixed; 			// Fix its position...
  top: 40px; 				// ...to about 40px from the top of the screen (just underneath the hamburger menu)
  z-index: 1000; 			// Put the menu on top of everything.
  min-height: 0;			// no minimal height, just long enough to contain all menu items 
}
body.global-nav-is-open #itrp-backdrop {
  display: block; 				// Show the backdrop
  position: fixed; 				// Fix its position...
  top: 0; bottom: 0; left: 0; right: 0; // ... to the entire browser window
  z-index: 999; 				// Put the backdrop on top of everything, except the navigation menu
}