/* hide tabs */
#main-window[tabsintitlebar="true"]:not([extradragspace="true"]):not([customizing]) #tabbrowser-tabs,
#main-window[tabsintitlebar="true"]:not([extradragspace="true"]):not([customizing]) #alltabs-button,
/* hide tst header */
#main-window:not([customizing]) #sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] > #sidebar-header {
    visibility: collapse !important;
}