I tried to keep this up for WordPress, and placing my CSS in the root instead of the theme folder, but this quickly changed. Mainly because it’s easier to manage when you have all your files in one folder (your theme folder). And also because it’s not the way it’s meant to be done.
You can use functions as bloginfo(“stylesheet_url”) to include style.css. The function generates a complete URL, which is great since you should always have a complete URL due to performance issues.