Index: src/wp-includes/css/editor.css
===================================================================
--- src/wp-includes/css/editor.css	(revision 50388)
+++ src/wp-includes/css/editor.css	(working copy)
@@ -4,7 +4,8 @@
 
 /* TinyMCE widgets/containers */
 
-.mce-tinymce {
+.mce-tinymce,
+.mce-top-part::before {
 	box-shadow: none;
 }
 
@@ -244,7 +245,7 @@
 
 /* TinyMCE toolbars */
 div.mce-toolbar-grp {
-	border-bottom: 1px solid #dcdcde;
+	border-bottom: 1px solid #c3c4c7;
 	background: #f6f7f7;
 	padding: 0;
 	position: relative;
@@ -1081,7 +1082,7 @@
 
 .wp-editor-container {
 	clear: both;
-	border: 1px solid #dcdcde;
+	border: 1px solid #c3c4c7;
 }
 
 .wp-editor-area {
@@ -1128,7 +1129,7 @@
 	height: 20px;
 	margin: 5px 0 0 5px;
 	padding: 3px 8px 4px;
-	border: 1px solid #dcdcde;
+	border: 1px solid #c3c4c7;
 }
 
 .wp-switch-editor:focus {
@@ -1230,7 +1231,7 @@
 .quicktags-toolbar {
 	padding: 3px;
 	position: relative;
-	border-bottom: 1px solid #dcdcde;
+	border-bottom: 1px solid #c3c4c7;
 	background: #f6f7f7;
 	min-height: 30px;
 }