@-moz-document url-prefix(chrome://browser/content/browser) {
    #appMenu-help-button.subviewbutton,
    #context-copylink,
    #context-copyimage-contents,
    #context-copyimage,
    #context-sendimage,
    #context-sendlinktodevice,
    #appMenu-notification-popup,
    #appMenu-update-banner,
    #context-savepage,
    #menu_savePage,
    #organizeBookmarksSeparator,
    /* 名前を付けてページを保存 */
    #main-context-menu-page-save,
    #main-context-menu-page-save *,
    #appMenu-save-file-button2,
    #appMenu-save-file-button2 *,
    #menu_savePage,
    #menu_savePage *
    {
        display:none !important;
    }
}

@-moz-document url-prefix(chrome://browser/content/places/places.xhtml) {
    #maintenanceButton
    {
        display:none !important;
    }
}