i have a site i im working on for my guild and to make the navigation border disappear on the selected item so that is is pure orange instead of having a black bar.
here is a pretty link, i have for review put the css in the document.
I am in a rush so I can't look through the code. But one of your CSS classes must have a border on it for the border to be there. Find it and remove it.
Looks a few people were quick to answer, but never looked at the code.
On #navagation, get rid of overflow: hidden. Then for .active_link you can set border-bottom to the shade of orange you need. Without getting rid of the overflow, the border part won't show up because it falls outside the overflow area.