Fixes inputs inside vertical menus, fixed black variable usage

src/definitions/collections/menu.less

@@ -201,16 +201,11 @@
 .ui.menu:not(.vertical) .item > .icon.input .icon {
   top: @inputIconOffset;
 }
-.ui.menu .item > .input input {
+.ui.menu:not(.vertical) .item > .input input {
   font-size: @inputSize;
   padding-top: @inputVerticalPadding;
   padding-bottom: @inputVerticalPadding;
 }
-.ui.vertical.menu .item > .input input {
-  margin: 0em;
-  padding-top: @inputVerticalPadding;
-  padding-bottom: @inputVerticalPadding;
-}
 
 /* Labeled Button */
 .ui.menu:not(.vertical) .item > .labeled.button > .icon {

src/themes/packages/default/collections/menu.variables

@@ -264,7 +264,7 @@
 ---------------*/
 
 /* Inverted */
-@invertedBackground: #333333;
+@invertedBackground: @black;
 @invertedBoxShadow: none;
 
 @invertedHeaderBackground: rgba(0, 0, 0, 0.3);