CSS in sharepoint -

I need to apply CSS in a Sharepoint site (WSS3.0) based on the topic applied to a site. CSS will be saved on the original site in 'Document Library'. How do I apply the CSS program to the page?

Thank you!

Place in a page layout or master page. E.g.

  & lt; SharePointWebControls: CssRegistration ID = "CssRegistrationMyCSS" name = "& lt;% $ SPUrl: ~ Site Collection / Style Library / ~ Language / Core Styles / myCSS.css% & gt;" Runat = "server" />  

Changing the programmatic way requires you to modify the control over page load. Not sure how well this will work.