CSS Help

There's no forum for this so I'm just gonna put it here...

Currently I am coding a site, and have a question about CSS. I remember having problems with this back in the day and I can't remember if I ever found an answer or anything, so here's the question.

How do I make it so the height of something is 100% of the page? Simply doing "height: 100%" doesn't work, is there a way to do 100% of the page or no?

[code]#site {
width: 695px;
height: 100%;
border: 1px #000000 solid;
background-color: #FFFFFF;
}[/code]

Not sure if this is just a noob question or what, thanks for any help / links.

I think you can use

padding-bottom : 0;