We never tested our theme in HTC 601, android, dolphin browser, so I assume it’s having the same issues as firefox mobile.
We only develop our theme in Window and Mac Desktop browsers, for mobile, we only use iPhone and iPad as standard devices, because they run the same iOS. Android devices have too many sizes and standards, and operating system is open source. Each company has a slightly different android operating system. We cannot use it as a development standard.
The above is my opinion, perhaps my colleagues has different opinion or solution.