add grayscale variables

src/Umbraco.Web.UI.Client/src/less/variables.less

@@ -69,6 +69,18 @@
 @green-l3:			    #A6F0CF;
 @green-washed:		    #EBFFF6;
 
+// Grayscale
+@gray-1:                #1E1C1C;
+@gray-2:                #303033;
+@gray-3:                #515054;
+@gray-4:                #68676B;
+@gray-5:                #817F85;
+@gray-6:                #A2A1A6;
+@gray-7:                #BBBABF;
+@gray-8:                #D8D7D9;
+@gray-9:                #E9E9EB;
+@gray-10:               #F3F3F5;
+
 
 // REMEBER TO UPDATE NAME ----- -- ---
 @test-purple: #F3F3F5;