Help editing nested comments

Hi, my site is electrotorials.com.

I am having troubles editing the layout of comments, especially nested ones. In ATO>Comments>style and configure comments, they give you the option to edit the boarder around single comments, and i changed it from dotted grey to a solid blue. But when I did, the nested comments still had a grey dotted border. I couldn't find anywhere to edit nested comments, any i would like to edit their spacing in relation to other comments as well as change the border.

In other posts i saw that the comments could be edited through a css insert:

ul.commentlist li {
margin: 5px 0;
padding: 10px;
border: solid 1px #419184;
background: #FFFCC8;
}

but when i did this, it made a box around a comment and all of its nested comments, additionally, it didn't replace the grey dot border.

If anyone could help me, I have wp 3.0.4 and Atahualpa 3.6.1