You mean fluid design so that everything expands or shrinks at different window resolutions?
Use % for widths of all elements like divs, tables, images, etc. including % widths for side margins and padding so that they total 100%.
Unfortunately borders cannot use % widths so if you have side borders in px you will need to allow space for them by totalling the % widths to 97% or 98%.
It can be tricky to get it working as images will resize heights automatically in proportion to the % width if you don't state a height for them, which is a good thing, but it may disrupt the layout for items below.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.