How to make IIS to deliver stylesheets with the correct MIME type?

Currently my IIS is serving CSS files with no Content开发者_StackOverflow-Type header. How to change it?

Should I change it on my application or in the server?

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This is definitly an IIS/OS function and should be set in IIS.

How to add it depends on the version of IIS you are using...

Here are instructions for IIS 6.0 and IIS 7.0.