Not all web editors are created equal. And to that end, I would introduce you to one called Amaya. Developed by W3C, this software supports all of the latest web standards and doe so with some pretty amazing grace.
As one might expect, both HTML and CSS are well supported, in addition to having the kind of user interface that will not overwhelm most users. Outside of that though, this really does not feel all that different that Bluefish or Nvu with regard to getting things done for most websites.
While I think the UI is a bit stronger here that with many of the open source HTML type editors, I am not totally sure that this is going to be a smooth transition for “unlearning” when it comes to the needs for most folks.