Not sure if the Personas (toolbar wallpaper) themes are for mobile Firefox also or only just desktop Firefox. Otherwise there is this section of addons.mozilla.org in case you were of Firefox section which is for desktop. https://addons.mozilla.org/en-US/mobile/personas/ Actually not sure if you need this Personas extension to use the Personas themes on mobile. However it has not been kept up to date. https://addons.mozilla.org/en-US/mobile/addon/personas/