diff --git a/src/wp-includes/css/editor.css b/src/wp-includes/css/editor.css
index ff6409ccf0..08c6d4c99b 100644
--- a/src/wp-includes/css/editor.css
+++ b/src/wp-includes/css/editor.css
@@ -13,9 +13,12 @@
 }
 
 /* TinyMCE windows */
-#mce-modal-block.mce-in {
+#mce-modal-block,
+#mce-modal-block.mce-fade {
 	opacity: 0.7;
 	filter: alpha(opacity=70);
+	-webkit-transition: none;
+	transition: none;
 }
 
 .mce-window {
@@ -24,6 +27,8 @@
 	-webkit-box-shadow: 0 3px 6px rgba( 0, 0, 0, 0.3 );
 	box-shadow: 0 3px 6px rgba( 0, 0, 0, 0.3 );
 	-webkit-font-smoothing: subpixel-antialiased;
+	-webkit-transition: none;
+	transition: none;
 }
 
 .mce-window .mce-container-body.mce-abs-layout {