.treeview-red li { background-image: url(images/treeview-red-line.gif); }
.treeview-red .hitarea, .treeview-red li.lastCollapsable, .treeview-red li.lastExpandable { background-image: url(images/treeview-red.gif); } 

.treeview-black li { background-image: url(images/treeview-black-line.gif); }
.treeview-black .hitarea, .treeview-black li.lastCollapsable, .treeview-black li.lastExpandable { background-image: url(images/treeview-black.gif); }  

.treeview-gray li { background-image: url(images/treeview-gray-line.gif); }
.treeview-gray .hitarea, .treeview-gray li.lastCollapsable, .treeview-gray li.lastExpandable { background-image: url(images/treeview-gray.gif); }