Newbie question about city borders: white borders vs. green borders

Hello everyone.

In my Civ3 Conquest multiplayer game, my city has expanded 2 times (because of the culture) but now the white border don't match the external green border, so I can't work the squares of my city outside the white borders... Why?
I have read the Civ3 manual and the Conquests manual but still I don't understand.

Thanks in advance for your help!

BYE

The border for your cities' workable land/source of shields will not expand past that point. The green border is your cultural border which will expand as you increase the cultural value of your city or cities.

In other words, you can only work the 21 squares inside the white border. The other squares are your territory thanks to culture, but the maximum workable area is never more than the 21. I hope this was some help.

Yep, every city has 21 tiles to work. The (in your case) green border is your territory border. Try to make all tiles in your territory border also tiles within a city's reach, so you don't waste anything in the territory. Especially on higher levels.