To me, including "mobile-first" as one of your key value proposition seems a little odd. My immediate reaction was to wonder whether any mobile browsers aren't

To me, including "mobile-first" as one of your key value proposition seems a little odd. My immediate reaction was to wonder whether any mobile browsers aren't mobile-first? From my (incomplete) knowledge of smartphone browsers they all feature interfaces designed for smartphones and smartphones alone. There must be a better word to use in your tagline - I notice you decided on using "Truly Mobile" further down ;)