Global Styles not working in iOS

I have the following global styles defined in app.xaml and applied on a content page (see attached). This works as expected in Android and UWP, but doesn't work in iOS. In Android and UWP the background is dark grey with a padding of 20. In iOS the background is white with no padding. None of the styles work at all in iOS, but the colors defined at the top do work in all platforms.