CSS Firebug Showing CSS That Doesn't Exist!

This has me baffled. I'm trying to change the colour of the dividers between my categories (the thin black horizontal lines above 'Womenswear' 'Menswear' and 'Childrenswear'). So, I open Firebug, inspect the page and click on one of the lines. It's showing me this:

hr {stylesheet.css (line 158)
border-color:-moz-use-text-color -moz-use-text-color #000000;
border-style:none none solid;
border-width:medium medium 1px;
height:1px;
margin-top:0.5em;
}

The weirdest thing I've seen yet is that none of my stylesheets contain any of this!!

Line 158 on my stylesheet.css is this:

HR {
height: 1px;
margin-top: 0.5em;
border: none;
border-bottom: 1px solid #000;
}

...........as you can see, it's nothing like Firebug says it is as it's missing the line I need to change (border-color:-moz-use-text-color -moz-use-text-color #e7e7e7;)

I've tried inserting the line into the sheet but even then, Firebug still shows the block of CSS that just doesn't exist?!

What gives folks? I've not come across anything like this yet... Usually when Firebug say's it's there, it's there?!?

Sounds like Firebug is adding in either the computed or user agent styles associated with the hr tag. Click on the options link top right of the Firebug pane and see if either is ticked.

Neither of those options are ticked....

I managed to do what I wanted at least by adding this:

hr.catBoxDivider1, hr.catBoxDivider2, hr#catBoxDivider {
border-color: #e7e7e7;
}

............. to my stylesheet_categories_dressing.css

You're right though, Firebug does seem to be computing it's own associated styles.. even though neither option is selected in Firebug Options Menu.

I suspect that it's having a senior moment and getting the defined styles a little mixed up with the browser defaults.