[eluser]fuchong[/eluser]
I'm not sure about how CI sessions and non-CI sessions work but what about the following?
Since the PHP files that you're calling are outside of the CI structure, they can accept query strings. Why not append a query string at the end and just use $_GET to grab what you want.
For example inside you're CI view
Code:
<link type="text/css" media="screen" rel="alternate stylesheet" title="Color Scheme #1" href="css-demo.php?scheme=alt1" />
And inside your dynamic CSS file
Code:
$scheme = $_GET['scheme'];
if($scheme == 'alt1'){
// do some CSS relating to alt1
}
else{
// do some other CSS
}