gtk3 - Can't set CSS to specified widget in GTK+ -

i'm using vala gtk+ , i'm trying add custom css specified widget. can add fe. backgroudn gtkwidget not #sidebar

#sidebar { //it doesn't work                                                                color: white;                                                                 }                                                                         gtkwindow {  // works                                                                         background-color: red;                                                                         }    

i'm adding class widget that:

sidebar = new gtk.label("hello"); sidebar.set_name("sidebar"); 

and it's changes color gtkwindow, not label.

any ideas?

i haven't programmed in vala, should add class stylecontext. in c

   sidebar = gtk_label_new ("hello');    gtk_style_context_add_class ( gtk_widget_get_style_context ("mysidebar"), sidebar); 

also, style "sidebar", defined in gtkstyle. should change "sidebar" in css else (sidebar used views, toolbar etc) if persist, syntax should be:

   .mysidebar {        #anything    }