Outra maneira, também baseada em userChrome.css
:
/* Colored folders for bookmark sidebar, toolbar, menu button */
/* Standard folder */
#bookmarks-view treechildren::-moz-tree-image(container),
#PlacesToolbarItems toolbarbutton[container="true"] .toolbarbutton-icon,
#PlacesToolbarItems menu[container="true"] .menu-iconic-left,
#BMB_bookmarksPopup menu[container="true"] .menu-iconic-icon {
fill: #e8bb00 !important; /* slightly muted gold */
}
/* Live Bookmark (RSS Feed) */
#bookmarks-view treechildren::-moz-tree-image(container, livemark),
#PlacesToolbarItems toolbarbutton[container="true"][livemark="true"] .toolbarbutton-icon,
#PlacesToolbarItems menu[container="true"][livemark="true"] .menu-iconic-left,
#BMB_bookmarksPopup menu[container="true"][livemark="true"] .menu-iconic-icon {
fill: orange !important;
}
/* Smart bookmark folder */
#bookmarks-view treechildren::-moz-tree-image(container, query),
#PlacesToolbarItems toolbarbutton[container="true"][query="true"] .toolbarbutton-icon,
#PlacesToolbarItems menu[container="true"][query="true"] .menu-iconic-left,
#BMB_bookmarksPopup menu[container="true"][query="true"] .menu-iconic-icon {
fill: #69c !important; /* similar to blue smart folder color */
}
/* These "containers" are SVG in the sidebar, not yet on the menu */
#bookmarks-view treechildren::-moz-tree-image(container, OrganizerQuery_BookmarksMenu) {
fill: olive !important;
}
#bookmarks-view treechildren::-moz-tree-image(container, OrganizerQuery_BookmarksToolbar) {
fill: olive !important;
}
#bookmarks-view treechildren::-moz-tree-image(container, OrganizerQuery_UnfiledBookmarks) {
fill: olive !important;
}
Esta solução vem de aqui .
Mais geralmente, userchrome.org parece ser uma fonte valiosa de informações (e receitas) sobre userChrome.css
.