For each page on the site I have a header and footer, so I decided to create a template for both then just include them on each page.
<?php include_once("header.php")?>
   contents of the page...        
<?php include_once("footer.php")?>
header.php contains:
<!DOCTYPE html>
<head>
<title>Items Page</title>
<link rel="stylesheet" href="assets/css/item.css">
<script src="assets/css/item.js"></script>
</head>
<body>
    <header>
        contains a navigation bar  
    </header>
footer.php contains:
    <footer>...</footer>
</body>
</html>
The above codes are for the Items page however I also have Users page they both have the same footer and header markup however different linked CSS and JS files. How can change <link> and <script> inside the <head> tag on the header.php include file if the user navigates to the user page, for example: mysite.com/user/blabla. 
The correct link for the Users page should be:
<link rel="stylesheet" href="assets/css/user.css">
<script src="assets/css/user.js"></script>
 
     
     
     
     
    