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I am starting to develop for all three major mobile platforms (Android, iOS, and Windows UWP), and have run into a UX issue a few times. Each platform has it's own design guide. Android has Material, Windows has Metro (I'm not sure what iOS's is called). Each design looks really good on its platform and only its platform. For example, Material looks beautiful on Android, but it would seem odd on iOS.
Now, I would like to follow these guidelines, and design per platform, but I feel that users would like it better if the app had a consistent design across all platforms. Furthermore, I also develop web apps, and since the web has no real "design guide", I would have to make yet another design. I could choose one design and make it universal across all platforms, but I feel like I would be performing some sort of "bad practice" to not use Metro and Material, and so on (plus, it may end up being harder to design and might look out of place).
In this scenario, what should I do? Use native styles for the different platforms, or create a single style, to be used across all platforms.