Sets z-index for .offline-ui to the maximum allowed value

When working with Bootstrap 3.1.1 I noticed that if you use a fixed navbar the Offline UI elements are obscured by Bootstrap elements. After a bit of frustration I realized that the z-index in Bootstrap was simply higher than that in Offline. Here I have a set the [z-index to the maximum allowed value] 
(http://softwareas.com/whats-the-maximum-z-index) in order to ensure the
UI elements always remain above any other elements rendered to the page.