diff --git a/web_parts/header.php b/web_parts/header.php
index 1bfc861..8a480b4 100755
--- a/web_parts/header.php
+++ b/web_parts/header.php
@@ -5,7 +5,7 @@
 <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" type="text/css">  
 
 
-<link rel="stylesheet" href="css/index.css" name="main-style" type="text/css">    
+<link rel="stylesheet" href="css/index.css?v=<?php echo filemtime(__DIR__ . '/../css/index.css'); ?>" name="main-style" type="text/css">
 <title><?php echo $global->title; ?></title>
 
 </head>