Use CSS to simulate Frame?

I've made a page which main contents is divided into 2 section:
#content and #additional. I put the #content floating left to the
#additiional so that they are sitting next to each other now.

My problem is, I want to put an image in the #content, which has a
fixed size of 200px*200px. So, it is better to fixed the height of the
#additional for visual appearance. Now my question is: Is there way to
use CSS to simulate a frame (so that I can have a fixed height of
contents)?

my example page is at:
http://personal.cityu.edu.hk/~505986...ning%206a.html

it contains the structure of the .html file. so pls look into the
source of it.

Thanks