Consistent and Usable Design/Template across all devices

I need a template Redesign for a site with 2 slight variations for search box . THE NEW TEMPLATE MUST SUPPORT AND WORK PERFECTLY ON ALL SCREEN SIZES RANGING FROM ALL DESKTOP SCREENS(15" - 32" OR EVEN MORE IF THERE ARE), MOBILE DEVICES(MOSTLY SMART PHONES 2.5" - 4 ") AND THE IN BETWEEN DEVICES LIKE NETBOOKS OR IPADS (9" - 12") ETC. There are plenty of ways to accomplish the above work, please mention how you're going to accomplish this in your bid. Please provide demo samples of your work specially if you have done something similar. Any bids that do not answer this question in their bid would be ignored. I already have a Design mock up which you could refine further to come up with an excellent layout and design. You must understand php as template page has php intermixed with html/css...although i can help you with this it's good if you know on your own. You would be paid once the template has been tested properly on all major browsers and everything checked. You should be able to start work today. .Reasonable bids with suitable experience/knowledge would be given preference.