Index: wp-admin/includes/media.php
===================================================================
--- wp-admin/includes/media.php	(revision 21223)
+++ wp-admin/includes/media.php	(working copy)
@@ -1157,7 +1157,7 @@
 	);
 
 	if ( $send )
-		$send = get_submit_button( __( 'Insert into Post' ), 'button', "send[$attachment_id]", false );
+		$send = get_submit_button( __( 'Insert into Post' ), 'button-primary', "send[$attachment_id]", false );
 	if ( $delete && current_user_can( 'delete_post', $attachment_id ) ) {
 		if ( !EMPTY_TRASH_DAYS ) {
 			$delete = "<a href='" . wp_nonce_url( "post.php?action=delete&amp;post=$attachment_id", 'delete-attachment_' . $attachment_id ) . "' id='del[$attachment_id]' class='delete'>" . __( 'Delete Permanently' ) . '</a>';