.sortDirectionIndicator[sortDirection="ascending"] > .treecell-header-box > .tree-header-sortdirection {
list-style-image: url("chrome://global/skin/sortAscending.gif");
.sortDirectionIndicator[sortDirection="ascending"] > .treecell-header-box > .tree-header-sortdirection {
list-style-image: url("chrome://global/skin/sortAscending.gif");