modals.less in bootstrap-generators-3.3.4

- old
+ new

@@ -60,13 +60,15 @@
   outline: 0;
 }
 
 // Modal background
 .modal-backdrop {
-  position: absolute;
+  position: fixed;
   top: 0;
   right: 0;
+  bottom: 0;
   left: 0;
+  z-index: @zindex-modal-background;
   background-color: @modal-backdrop-bg;
   // Fade for backdrop
   &.fade { .opacity(0); }
   &.in { .opacity(@modal-backdrop-opacity); }
 }