ほれ
treechildren::-moz-tree-cell-text(container, OrganizerQuery_UnfiledBookmarks) {
color: transparent !important;
}
treechildren::-moz-tree-image(container, OrganizerQuery_UnfiledBookmarks) {
list-style-image:none !important;
}
treechildren::-moz-tree-twisty(container, OrganizerQuery_UnfiledBookmarks) {
list-style-image:none !important;
}