Fix for Gberg RC.

apostrophe-2/css/editor-blocks.css

@@ -148,10 +148,8 @@
 
 /* Main column width */
 
-body.gutenberg-editor-page .edit-post-visual-editor .editor-post-title__block,
-body.gutenberg-editor-page .edit-post-visual-editor .editor-default-block-appender,
-body.gutenberg-editor-page .edit-post-visual-editor .editor-block-list__block:not([data-align=wide]):not([data-align=full]) {
-	max-width: 730px;
+.wp-block {
+	max-width: 760px; /* 730px + 30px padding */
 }
 
 /* Link styles */