One of my clients noticed a very thin light line and a very thin dark line in the active link on their navigation bar. It's barely noticeable, but it's there. I've tried tweaking the CSS, but since the lines are less than a pixel wide, I'm not sure that it's the CSS.

Here's the url: <http://www.abqlibraryfoundation.org>

If you look at the "Home" link in the navigation bar, you'll see that as the active page, it's a rusty orange color and it has a thin light edge on the left side. The right side has a dark thin edge in between the orange and turquoise colors.

Does anyone know what's causing this?