Firefox hide tabs bar and address bar

userChrome.css

/* Hide tabs and title bar */
#TabsToolbar {
    visibility: collapse;
}

#titlebar {
    margin-bottom: -25px !important;
}

#titlebar-buttonbox {
    height: 32px !important;
}

#nav-bar {
    margin-right: 42px;
}

#main-window[sizemode="maximized"] #nav-bar {
    margin-right: 42px;
}

/* "Auto-hide" address bar unless focused (e.g. Ctrl-L) or tab bar is hovered. */
:root {
    --address-bar-height: 40px;
    --browser-offset: calc(-1 * (var(--address-bar-height) + 1px));
}
#navigator-toolbox-background {
    position: absolute !important;;
}
#navigator-toolbox-background ~ #browser {
    margin-top: var(--browser-offset) !important;
}
#navigator-toolbox-background:hover, #navigator-toolbox-background:focus-within {
    z-index: 9001 !important;
}