You can set every element (divs, forms, tables, lists) with a width in ems and then when someone increases text size the divs, images and everything incraese in size as well.
However, this does cause problems with images as the height may change in height out of proportion to elements around them, or if you leave images in fixed sizes, they don't fit the changed containers.
Modern browsers have a zoom which increases the whole page including images, so I think it's better now to code font and divs and images in fixed sizes and widths and let a viewer use page zoom instead of text increase and then everything stays in proportion.
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.