UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? Add logo image to board

I think you'd actually need to reference a script for the header_custom.gif file. That script would check the current date and then display the proper image.

So, something like:

background: url(/path/to/header_custom.php) no-repeat 50% 0;

And then the header_custom.php script would output the proper image.