Is CSS the ultimate expression of progressive enhancement?

Following up on my previous post about progressive enhancement, I wish to pose the question:
Is CSS the ultimate expression of progressive enhancement?

To help us address the question, lets briefly remind ourselves that progressive enhancement is a technique whereby the way a web page operates is enhanced if the user agent being used supports certain features but if the user agent does not, then nothing is lost. The user can still see all content and use all features of the web page.

So, does this hold true of CSS? Well, given valid markup, I believe it does and I certainly believe it should.

That does not answer the question posed though. I am firmly of the opinion that the answer is yes. CSS is so powerful and so able to change the way a web page looks but without itself forming any part of the content or functionality of that web page, that I believe it must be the ultimate expression of progressive enhancement.

Do you agree? Do you disagree?