CSS based images?

[supersteve3d]

Hi all. Apologies in advance but perhaps my brain is fried.

I have image replacement working pretty well for text. So when CSS is disabled, the page still has text and makes sense. The whole reason for me to go fully CSS was to allow me to easily swap files in future for changing my design radically.

Here is the silly question of the day.
How do I say swap graphics headers alone when there is no text at all? From what I see, the img source seems to be always defined in the html and not in the css file?

What I want is something like <img id="xx"> where I can vary the source image by changing the css file. So far it seems that <img id="xx" src="yy"> (source must be defined?) If so, how can I avoid hardcoding the path to source in html?

I guess the approach is to use an empty <div id="yy"></div> to place headers where the source is defined in css? Is this the accepted approach?

My guess is I have the wrong assumptions.

Thanks.

[NogDog]

The only way via CSS would be if it were a background image, as far a I know.