Timeless should use message box styles from core

Bug: T304768
Change-Id: I0003d58b097514eb22a9932539a2f4d4eac47545

resources/libraries/shared.css

@@ -366,48 +366,6 @@ a.new {
 	color: #14866d;
 }
 
-.messagebox,
-.errorbox,
-.warningbox,
-.successbox {
-	color: #000;
-	margin-bottom: 1em;
-	border: 1px solid;
-	padding: 0.5em 1em;
-}
-
-.messagebox h2,
-.errorbox h2,
-.warningbox h2,
-.successbox h2 {
-	color: inherit;
-	display: inline;
-	margin: 0 0.5em 0 0;
-	border: 0;
-	font-size: 1em;
-	font-weight: bold;
-}
-
-.messagebox {
-	background-color: #eaecf0;
-	border-color: #a2a9b1;
-}
-
-.errorbox {
-	background-color: #fee7e6;
-	border-color: #d33;
-}
-
-.warningbox {
-	background-color: #fef6e7;
-	border-color: #fc3;
-}
-
-.successbox {
-	background-color: #d5fdf4;
-	border-color: #14866d;
-}
-
 /* general info/warning box for SP */
 .mw-infobox {
 	border: 2px solid #fc3;

skin.json

@@ -66,7 +66,7 @@
 				"content-tables": false,
 				"interface": false,
 				"interface-category": false,
-				"interface-message-box": false,
+				"interface-message-box": true,
 				"elements": false,
 				"legacy": false,
 				"i18n-ordered-lists": true,