screen resolution!

Hi, I have written a website in PHP using MYSQL. But I have come accross an un-common problem. Normally when I create a website it's done on a desktop PC. But this time for the first time I did it on laptop meaning the screen resolution is different. Is there any sort of script/code I can use to create another section of my site in a desired screen resolution without me having to do it all manually? I know of many scripts online that I can DETERMINE visitors screen resolutions and recommend the correct one but don't know one that will adjust the website to suit that visitors screen resolution. Am aware of scripts that redirect to another web page but that requires you to write the website again to cater for that. Is there a quicker way/solution? Thanks! J