Change part of the CSS iwth an <input> box?

Hi,

I'm trying to make a resizable DIV, where you can type in the width and height, and it'll change automatically, before your eyes (without having to reload the page)

Is there a way to do this? Let's just say I have a square that is 100 x 100px. There are two text boxes below it, one showing the height, the other, the width. In the height box, you delete 100 and put in 200. Now the box is 100 x 200px. It does this by changing the box's (the DIV) CSS, because my box has a CSS property that shows how big it is. This CSS file is external, so it's something.css.

Is this possible? I think it is, but I've searched and found nothing.

Thanks!