GetAttribute Isn't Getting The Attribute

I'm trying to get the value of an object's property. getAttribute returns "null" even though I'm sure the property is set. I can easily set the property, and in my actual script I do so dynamically. I just want to read the property and can't.

To help explain my problem, I've attached an example .html file as a .txt file.

The critical part of the code is this section that is based on "textbook" examples of how to get an attribute:

<script type="text/javascript">
function
showcolor() {
var myobject = document.getElementById("lab");
var myproperty = myobject.getAttribute("color");

alert(myproperty);
}
</script>

This is called via a button on the bottom of the page. The DIV object with the ID "lab" exists and has a color attribute defined in CSS, but I cannot read it, nor any other attribute, with a script. The alert displays "null".