KDDI's high-end Firefox OS phone, the Fx0 (pictures) BARCELONA -- The Fx0 from Japanese carrier KDDI is the top-end Firefox OS phone on the market. Here's a look at the transparent-backed design. Mozilla showed it off at Mobile World Congress. Stephen Shankland worked at CNET from 1998 to 2024 and wrote about processors, digital photography, AI, quantum computing, computer science, materials scien