Change GridView cell color

Hello All,
My Page has a Gridview and a Servertimer control.
Gridview cells color should change if server time elapses.
Say for example, My ServerTime is 7.35 AM
If my Cell value is "7.31.00" means it elapsed when compared to ServerTime, so I need its color to change "Red".
else I would be in same Khaki color.
Any help would be much useful.
Thanks,
Vidhya.