Making header fluid

I did find this information in the codex:

“If you are designing a Theme with a flexible or “elastic” screen width, then the width of your header becomes important.

“If you are using a header image that can be repeated, and you are using elastic widths, you can set the styles within the header to repeat to fill the space:

#header {
background: url(“/images/kubrickheader.jpg”)
repeat-x top left; }

“This sets the header image to repeat horizontally beginning from the top left corner and going across. You can adjust these to whatever background position (https://www.w3.org/TR/REC-CSS2/colors.html#background-properties) your header design and layout needs. :

However, it does not address what to do if you are using a fluid/elastic theme and a header image that cannot be repeated (as in my case).

Chris