. With a combination of positioning, floating, margins, padding and borders, you should be able to represent ANY web design and there is nothing that can be done in tables that can not be done with CSS.
The CSS clear property is used to for control flow when using the float property. Using CSS clear, you can specify whether to keep one or both sides of an element "clear" (i.e. no elements can appear on the side that is clear).
none - floating elements can appear on either side
left - floating elements can not appear on the left (i.e. keep the left side "clear")
right - floating elements can not appear on the right (i.e. keep the right side "clear")
both - floating elements can not appear on the left or right (i.e. keep both sides "clear")