Fix internal borders, remove border from fixed

src/definitions/collections/menu.less

@@ -1480,7 +1480,6 @@ Floated Menu / Item
   position: fixed;
   z-index: 101;
   margin: 0em;
-  border: none;
   width: 100%;
 }
 .ui.menu.fixed,
@@ -1491,12 +1490,14 @@ Floated Menu / Item
 
 .ui.fixed.menu,
 .ui.top.fixed.menu {
+  border-top: none;
   top: 0px;
   left: 0px;
   right: auto;
   bottom: auto;
 }
 .ui.right.fixed.menu {
+  border-right: none;
   top: 0px;
   right: 0px;
   left: auto;
@@ -1505,12 +1506,14 @@ Floated Menu / Item
   height: 100%;
 }
 .ui.bottom.fixed.menu {
+  border-bottom: none;
   bottom: 0px;
   left: 0px;
   top: auto;
   right: auto;
 }
 .ui.left.fixed.menu {
+  border-left: none;
   top: 0px;
   left: 0px;
   right: auto;

src/themes/default/collections/menu.variables

@@ -41,7 +41,7 @@
 
 /* Divider */
 @dividerSize: 1px;
-@dividerBackground: @borderColor;
+@dividerBackground: @internalBorderColor;
 
 /* Sub Menu */
 @subMenuDistance: 0.5em;
@@ -203,7 +203,7 @@
 @verticalPointerWidth: 2px;
 @verticalBackground: #FFFFFF;
 @verticalItemBackground: none;
-@verticalDividerBackground: @borderColor;
+@verticalDividerBackground: @dividerBackground;
 
 @verticalActiveBoxShadow: none;