diff --git a/doc/index.html b/doc/index.html
index abf11b59a..b98e83715 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -1,8 +1,8 @@
+<!DOCTYPE html>
 <!-- 
 SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
 SPDX-License-Identifier: Apache-2.0
  -->
-<!DOCTYPE html>
 <html>
   <head>
     <title>API Reference | ReDoc</title>
