Dec 13th, 2018: Note that there is no need to use this solution in today’s modern browsers. You should feel free using the answer below mine li:not(:last-child) { border-bottom: 1px solid red; }
Without using JavaScript and not having to support IE7 and below (IE8 fails on the second one) there are three options you can use: :first-child, :lastchild and the + selector:
:first-child
li { border-top: 1px solid red; }
li:first-child { border-top: none; }
:last-child
li { border-bottom: 1px solid red; }
li:last-child { border-bottom: none; }
+ selector
li+li { border-top: 1px solid red; }
The problems arise if you need to support IE8 and your design doesn’t allow you to put a border on the top of your elements as opposed to the bottom.
EDIT:
The fix to your width issue is that you’re adding 180px to 2*18px of the a element, remove the left right padding, and set padding: 18px 0; and you’ll be golden. (updated jsfiddle: http://jsfiddle.net/NLLqB/1/)
Here’s a jsfiddle of it: http://jsfiddle.net/NLLqB/