Box with Two colors Logic

Hi
 
I am working in asp.net 4.0(VS2010)
 
I have two values  1. Maximum Amount 2. Reached Amount
 
I have to show a box with two colors(Dark Green and Light Green)  and based on the % of reached amount i have to increase the reached amount color. Also inside the box i have show the label with reached amount.
 
 
Let us take an example of  Max Amount : $50 and Current Reached Amount : $25. So now my box should be filled with Dark Green color half the size of box and Light Green filled with half size of box and have to show the label as "Reached amount: $25" inside the box.
 
Then tomorrow if reached amount is $35 then Dark green color should be increased and light green should be reduced based on the % of increase. as like this based on increased and decreased calculation the colors have to filled.
 
W ...