The wizard behind the curtain
The platform WebView is especially inconsistent between Android OS versions. Something that works perfectly on Android 4.2 might not work on Android 4.1 simply because a feature is not implemented, and a rendering bug might require a workaround only on Android 4.3.
To fix this, we have partnered with Intel to integrate their Crosswalk project in AppGyver Wrapper for Android. Crosswalk WebViews use the latest version of Chrome, giving you access to all the newest HTML5 features. More importantly, apps built with Crosswalk behave consistently on all devices, regardless of Android OS version.
As for the rest of the issues, the Supersonic Framework takes care of them. Supersonic is crafted to ensure that your CSS scales nicely to multiple resolutions, that APIs work consistently on both Android and iOS, that native UI elements use the unique design paradigms of each platform, and much more.