I have a header file that is linked to a css file. When I run the header file it displays exactly as I want. I therefore know that the css and header file are working. When I include the header in my index.php the css is ignored and the header displays incorrectly. 

In the header file I import the css as: 

```
<link rel="stylesheet" href="css/style.css">

```

and in index.php I import the header as: 

```
<?php include("header/header.php"); ?>

```

Any ideas what I need to do so that the css is also included so that the page will display correctly? My header.php is inside a header folder, which also includes the css folder.