Fluid textarea?

I am working on a fluid three-column theme right now. Everything is shaking out except for an issue with the comment textarea.

Everything works fine in FireFox, the textarea expands and collapses as the browser window is resized, just as it does in IE 6.2. The problem is, when I use IE, the moment I start typing in the textarea, it expands across the page.

I know this is a CSS thing and I have the following instructions in my stylesheet:

#commentform textarea
{
width: 95%;
}

I searched for this topic here and found the following to add:

*html #commentform textarea {
width: 600px;
}

This kinda defeats my purpose of having a fluid design for my site, if I have to have a fixed object size for IE. I tried cheating a little by tweaking the IE instruction so that it reads like this:

*html #commentform textarea {
width: 50%;
}

But all that does is expand the textarea to a maximum width of my column when I am typing.

I guess my question is, — is there a better instruction for fixing this problem?

You can see what it is doing here:

https://www.donotspam.org