convert website into responsive layout

Our newly launched site is coded in complete CSS/XHTML and we are looking to have it optimized to be a fully responsive layout that adjusts to mobile devices and tablets. The site is never 100% complete, but the basic design elements will not change, however we will have a few added features and subpage layouts included in our design that will need to be changed. Some features of the design will have to be removed at lower resolutions in order to allow the ease of use and functionality to continue on smaller devices. Graphics will need to scale based on resolutions as well, in order to ensure ease-of-use. We are only looking for people with EXPERIENCE with this sort of project, this is not a learning experience and we need it done as quickly as possible. Our site works with numerous PHP scripts that include content from various areas of our site, so this will be expected to be maintained. Revisions can be made to the site if need be to make the content responsive, however this will entire be your job. Please send a message if you are interested in the URL, and then you can place your bid, indicating the time frame, other responsive pages you have worked on (provide examples of WORKING PAGES), and your pricing. A MAXIMUM (READ THIS) of 50% will be put down as a milestone, and WILL NOT BE RELEASED UNTIL WORK IS COMPLETED.