Component width 100% ?

Denise Bowker

First of many newbie questions....
Trying to create a component which has a width of 100% not a fixed pixel width.

My component is made up of two divs one with float:left, one with float:right and the component will be in a liquid area.

If the answer is "RTFM" please enlighten me with which manual and which section/page. I've spent most of the afternoon trying to find it.