Apply restyling to Php website

Hello, We've to restyle a website for our customer, we will provide the graphical layout for the restyling already made in clear html+css, we need someone enough skilled with PHP to apply the graphic we provide to a set of about 20/30 php pages of the existing website. Html is located in each PHP page, no templating system. There are some forms and dynamic data in the pages so graphical layout have to be changed keeping all the existing php stuff working (so nothing to code).