If you’re a Mac user google TinkerTool. It’s a free application which can reveal hidden files with a couple of mouse clicks. And it’s not scary like the Terminal (though it might just be me that thinks that).
You need to add the extra 3px of padding-left to the li:hover not to the a:hover. Remove the padding-left: 8px from the ul#sidebar li a:hover declaration. And in the ul#sidebar li:hover declaration change the width to 197px and add padding-left:3px;