Disclaimer: I used Xamarin Forms and C# for the first time for a project!
When doing that I noticed that my app looks very different on an phone and a tablet. I was in need for something to position and scale ui elements percentually in a general way. Therefor I came up with a couple of utility classes, which I thought to put out there for others who may need it.
An example Xamarin project can be found at github repo
I'm happy to know if you find it useful or useless