<?xml version="1.0" encoding="utf-8"?>
<Application xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:d="http://xamarin.com/schemas/2014/forms/design" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="XamarinApp.App">
    <Application.Resources>

        <Style x:Key="BaseButtonStyle" TargetType="Button">
               <Setter Property="TextColor" Value="White" />
               <Setter Property="BorderWidth" Value="1" />
               <Setter Property="BorderColor" Value="Blue" />
               <Setter Property="FontSize" Value="20" />

        </Style>

        <Style x:Key="RedButtonStyle" TargetType="Button"
            BasedOn="{StaticResource BaseButtonStyle}"> 
            <Setter Property="BackgroundColor" Value="Red" />
         </Style>

    </Application.Resources>
</Application>