You're probably forget add
PHP Code:
<link href="style.css" rel="stylesheet" type="text/css">
To the head tag of main page
or it's point to wrong filename, or file that not lie in this directory.
[edit]
Not dl this stuff, since i can't now
, but style.css is in templates directory, so you probably must change
"style.css", to "templates/style.css"
[/edit]