chaning link color using css

Hi, all, I've 3 frames, which is Top, Left and Main Frame. What I wanted to do is when I click on the link on the first frame, I would like to change the link color from 'blue' to 'green', then when I click on the link on the 2nd frame, I would like the link color on the first link stay as 'Green' and the link on the second frame also change from blue to 'Green'. Then when I click on the link on the 3rd Frame, I still would like to have the first link, second link stay 'Green', and the link color on the 3rd frame also change from 'blue' to 'green' so the users know which topic they are browsing at the meantime.

Thanks in advance for all your help.

Titi