Problems Accessing CSS Attributes With JS

I'm having an issue with CSS, JS and the DOM. It's gonna drive me batty. I
am trying to access the properties of a layer in JS which have been
initially set in an external CSS. The problem is that for some reason JS
isn't receiving NULL for all the properties of the layer. For instance:

HTML
<div id="blarg">.....</div>

JS
var t = document.getElementById("blarg").style.left;

CSS
#blarg{
position: absolute;
left: 200px;
}

t == NULL and I can't figure out why. It is this way for any CSS attribute
I attempt to read (width, positional, the whole kit and caboodle).

It does work if I set the attribute in JS before I read it.

JS
document.getElementById("blarg").style.left = 30;
var t = document.getElementById("blarg").style.left;

t now == 30. The only thing I can think of to explain this is that when
the document gets loaded my layers aren't getting their attributes filled
out. The object gets created and the attribute fields are blank until I
fill them in. Thusly my creation of CSS's was a waste of time. Grr...

Any ideas/suggestions? Google has been of no help. :-( This is occurring in
IE 6, and the gecko engine browsers.