MainPageButtons.xaml.cs

using System;
using System.Collections.Generic;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace Saplin.CPDT.UICore
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class MainPageButtons : StackLayout
    {
        public MainPageButtons()
        {
            InitializeComponent();
            Application.Current.Resources["refreshButton"] = refreshButton;
        }

        public void AdaptLayoytToScreenWidth(bool narrow)
        {
            foreach(var c in Children)
            {
                if (c is Button)
                {
                    if (narrow)
                    {
                        (c as Button).Style = Application.Current.Resources["NarrowButtonStyle"] as Style;
                    }
                    else
                    {
                        (c as Button).Style = Application.Current.Resources["ButtonStyle"] as Style;
                    }
                }
            }
        }
    }
}