sugestion

[Karl]

you can put a system to only change style base like in phpbb2 but for phpbb3? this is to not to be hours installing mods in all the styles will more easy for me install only in the style base, and my users personalizing your own style

here a screen shot

[CyberAlien]

Its impossible because every style uses its own css, there isn't a set of predefined variables. However there is a css editor and its available to users.

[Karl]

mmmm not is possible ok thanks