Is there any application like Web Developer or similar that makes it possible to backtrace css applications? What I mean is:

Say I have this span.class, and it has been styled from different sheets, say sheet1.css, sheet2.css, and also from some inline styles:
HTML Code:
<link href="sheet1.css"/>
<link href="sheet2.css"/>

<body>
<span class="class" style="color: red"></span>
</body>
Code:
/* sheet1.css */
.class {color: blue;}

/* sheet2.css */
.class {color: yellow;}
Sometimes it'd be really nice to have some kind of tool of backtracing the styles; to know from where the different styles came, and in what order.

I am right now in the middle of a pretty big e-commerce web application and the CSS nest is getting rather nasty. Combined with different browser bugs, I've had some really tough problems.