ul.tree li {
    list-style-position: inside;
    margin: 0;
    line-height: 1.2;
}
ul.tree li.tree-collapsed > ul {display: none;}
ul.tree li.tree-branch {
    list-style-image: url(tree-branch.png);
}
ul.tree li.tree-collapsed {
    list-style-image: url(tree-collapsed.png);
}
ul.tree li.tree-leaf {
    list-style-image: url(tree-leaf.png);
}