another quick pass at ranking all zindexes and listing them in variables for quick overview and editing later

lib/dropdowns.less

@@ -27,7 +27,7 @@
 .dropdown-menu {
   position: absolute;
   top: 40px;
-  z-index: 1000;
+  z-index: @zindexDropdowns;
   float: left;
   display: none; // none by default, but block on "open" of the menu
   min-width: 160px;

lib/modals.less

@@ -7,7 +7,7 @@
   right: 0;
   bottom: 0;
   left: 0;
-  z-index: 10000;
+  z-index: @zindexPopover;
   background-color: @black;
   // Fade for backdrop
   &.fade { opacity: 0; }

lib/navbar.less

@@ -125,7 +125,7 @@
   top: 0;
   right: 0;
   left: 0;
-  z-index: 999;
+  z-index: @zindexFixedNavbar;
 }
 
 

lib/popovers.less

@@ -5,7 +5,7 @@
   position: absolute;
   top: 0;
   left: 0;
-  z-index: 1005;
+  z-index: @zindexPopover;
   display: none;
   padding: 5px;
   &.top    { margin-top:  -5px; }

lib/twipsy.less

@@ -3,7 +3,7 @@
 
 .twipsy {
   position: absolute;
-  z-index: 1005;
+  z-index: @zindexTwipsy;
   display: block;
   visibility: visible;
   padding: 5px;

lib/variables.less

@@ -44,7 +44,16 @@
 @siteWidth:         (@gridColumns * @gridColumnWidth) + (@gridGutterWidth * (@gridColumns - 1));
 
 // Fluid width sidebar
-@fluidSidebarWidth:	220px;
+@fluidSidebarWidth: 220px;
+
+
+// Z-INDEX
+// -------
+@zindexDropdowns:     1000;
+@zindexTwipsy:        1000;
+@zindexFixedNavbar:   1010;
+@zindexPopover:       1020;
+@zindexModal:         1030;
 
 
 // THEME VARIABLES