diff --git a/cis/private/lehre/lesson.php b/cis/private/lehre/lesson.php
index 4d8c872a1..8ac751ba3 100644
--- a/cis/private/lehre/lesson.php
+++ b/cis/private/lehre/lesson.php
@@ -102,6 +102,7 @@ if (isset($_GET["handbuch"])){
 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 	<link href="../../../skin/style.css.php" rel="stylesheet" type="text/css">
 	<link href="../../../skin/jquery.css" rel="stylesheet" type="text/css"/>
+	<link href="../../../vendor/components/jqueryui/themes/base/jquery-ui.min.css" rel="stylesheet" type="text/css"/>
 	<script type="text/javascript" src="../../../vendor/jquery/jqueryV1/jquery-1.12.4.min.js"></script>
 	<script type="text/javascript" src="../../../vendor/christianbach/tablesorter/jquery.tablesorter.min.js"></script>
 	<script type="text/javascript" src="../../../vendor/components/jqueryui/jquery-ui.min.js"></script>