This phrase is a semantic minefield. Some people hang up when they hear this. Can we relax a little? The people who say this do understand that form and function are part of each other.

Let's change the wording and see if it helps. What we're doing -- what the very nature of the web requires -- is to separate data from layout at a code level. Style is not trivial nor divorced from your message. It's just that the multi-viewer nature of the web requires multi-viewer consideration for your data. So you have to think about what's data, what's layout.

In code terms, data is what goes in your HTML. If it's not your core text and absolutely necessary images, strip it out of there. Layout is what goes in your CSS. Colors, fonts... tone rate & gender for voice readers... you name it, that all goes in CSS files.

This is not, in any way, a belittling of style. Style is entwined with content. It's just that there's a lot of options beyond screen layout, so momentarily separating these terms is necessary to help you make choices for the many media without blocking out any media."