I recently finished reading the excellent book Resilient Web Design, by Jeremy Keith.
At one point, in the 5th chapter, the author was discussing whether the websites should all look the same in every browser or not.
The answer – in the view of the Jeremy – is no:

New browsers and old browsers; monochrome displays and multi‐coloured displays; fast connections and slow connections; big screens, small screens, and no screens; everyone can access your content. That content should look different in such varied situations. If a website looks the same on a ten‐year old browser as it does in the newest devices, then it probably isn’t taking advantage of the great flexibility that the web offers.

Then I remembered about this manifesto of Barry Smith (not quite safe for work):

Something was not right. Barry and Jeremy were talking about the same thing (I can even see a picture of them singing together), but the message was different. So, is a website supposed to look the same in every browser or not? The answer is here:
DoWebsitesNeedToLookExactlyTheSameInEveryBrowser.com

The explanation: presentation vs content

When we say ‘look the same’ we refer to the presentation. And, as Jeremy said, it would be stupid if the look of your website would not take advantage of the new flexibility that the web offers. So the visual aspect should not look the same in every browser.

The content on the other hand should be the same in every browser. If some content or functionality is missing in some old browser or platform, you did something wrong. And that’s what Barry was referring to – his message (aka content) is the same on the latest Macbook or on a Tamagotchi.

So, websites should not look the same in every browser, but their message should still be transmitted in all the cases. And that’s what progressive enhancement is all about.

The take-away

Leaving the presentation vs content debate aside, I think the most important message sent by Jeremy in his recent book (BTW – it’s free) is his 3-step approach that defines the ‘resilient’ design:

1. Identify core functionality.
2. Make that functionality available using the simplest possible technology.
3. Enhance!

PS: I’m happy I had the chance to meet Jeremy during the Smashing Conference in Freiburg (September 2014). Here is a picture that I took while he was talking to Pete Smart:

My full flickr album with photos I took during the conference.