CSS file to be change in two different versions

Note: This project is urgent and if you cannot deliver within 4 hours, do not bid. We are very serious on work and kindly do not waste our time. Our designer went for holidays and so that is why we are hiring here. So, do good work and get all our designer work over this holiday season. We have an already completed website with css files which manage the color combination. Now, we need the css file edited so that it brings about two different color combinations of the website. Note: You will not change the layout of the website at all. Just the color combination. We will provide the two other combination in image form and we have already duplicated the website into other two website which need different color combinations. Simple: Bid reasonaly, get this work within 20 minutes, start the work immediately, and deliver within 4 hours.