Two elements with the same class look different in Firefox

I have two <hr>with the same class as well as with other attributes that look the same in Chrome, etc. However, for some reason, in Firefox, the one at the bottom of the page looks like, but the one at the top is twice as large.

Any ideas? I am also open to other suggestions if they work better to create a black line 2.5px high.

The problem on every page is http://www.duncannz.com - the black line at the top looks too thick in Firefox, but the black line at the bottom is fine. Both lines in any other browser are good.