Remove @black and just use #000

docs/assets/css/bootstrap.css

@@ -2277,7 +2277,7 @@ table th[class*="span"] {
   width: 0;
   height: 0;
   vertical-align: top;
-  border-top: 4px solid #000000;
+  border-top: 4px solid #000;
   border-right: 4px solid transparent;
   border-left: 4px solid transparent;
   content: "";
@@ -2388,7 +2388,7 @@ table th[class*="span"] {
 .dropup .caret,
 .navbar-fixed-bottom .dropdown .caret {
   border-top: 0;
-  border-bottom: 4px solid #000000;
+  border-bottom: 4px solid #000;
   content: "";
 }
 
@@ -2517,14 +2517,14 @@ table th[class*="span"] {
   font-size: 20px;
   font-weight: bold;
   line-height: 20px;
-  color: #000000;
+  color: #000;
   text-shadow: 0 1px 0 #ffffff;
   opacity: 0.2;
   filter: alpha(opacity=20);
 }
 
 .close:hover {
-  color: #000000;
+  color: #000;
   text-decoration: none;
   cursor: pointer;
   opacity: 0.4;
@@ -4133,7 +4133,7 @@ input[type="button"].btn-block {
   bottom: 0;
   left: 0;
   z-index: 1040;
-  background-color: #000000;
+  background-color: #000;
 }
 
 .modal-backdrop.fade {

less/close.less

@@ -8,11 +8,11 @@
   font-size: 20px;
   font-weight: bold;
   line-height: @line-height-base;
-  color: @black;
+  color: #000;
   text-shadow: 0 1px 0 rgba(255,255,255,1);
   .opacity(20);
   &:hover {
-    color: @black;
+    color: #000;
     text-decoration: none;
     cursor: pointer;
     .opacity(40);

less/dropdowns.less

@@ -20,7 +20,7 @@
   width: 0;
   height: 0;
   vertical-align: top;
-  border-top:   4px solid @black;
+  border-top:   4px solid #000;
   border-right: 4px solid transparent;
   border-left:  4px solid transparent;
   content: "";
@@ -135,7 +135,7 @@
   // Reverse the caret
   .caret {
     border-top: 0;
-    border-bottom: 4px solid @black;
+    border-bottom: 4px solid #000;
     content: "";
   }
   // Different positioning for bottom up menu

less/modals.less

@@ -10,7 +10,7 @@
   bottom: 0;
   left: 0;
   z-index: @zindex-modal-background;
-  background-color: @black;
+  background-color: #000;
   // Fade for backdrop
   &.fade { opacity: 0; }
 }

less/variables.less

@@ -9,7 +9,6 @@
 
 // Grays
 // -------------------------
-@black:                 #000;
 @grayDarker:            #222;
 @grayDark:              #333;
 @gray:                  #555;