Css template caching

[scarex]

Hello Everybody,
I've tried to put a global variable (that can be set in vbulletin options panel) in vbulletin.css template, but even if I change the variable value, the final css doesn't change, I assume because of caching system.

I've to "modify" css template in some one in order to be regenerated.

Instead, if I modify a style variable (like a color or background image) css is directly generated.

Is there a mechanism to force css to be regenerated, so I and my staff can modify, for instance, backgroun image from vbulletin options panel?