styling widget / sidebar bullets

I’m trying to style the bullets in my sidebar so they will not show up on the first level of a UL, only on subsequent levels. I’m an html beginner, so I need some help. I’ve found the file I need to edit (style.css of my theme, Shades of Blue), and the sections under “sidebar” where the bullet gif appears. If I remove the background line from either or both of those two sections (see below), the bullet disappears from all levels, but I haven’t been able to figure out how to get it to disappear only from the top level. Help!

#sidebar ul li li {
	background: url(images/arrow.gif) no-repeat top left;
  padding: 0px 0px 0px 15px;
	margin: 0px 0px 0px 0px;
	}

#sidebar ul li ul li {
  background: url(images/arrow.gif) no-repeat top left;
  padding: 0px 0px 0px 15px;
	margin: 0px 0px 0px 0px;