Xamarin.Forms-Samples/ResourceDictionaries/Styles/ButtonStyles.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ResourceDictionary xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Styles.ButtonStyles">

    <Style x:Key="SharedButtonStyle" TargetType="Button">
        <Setter Property="BackgroundColor" Value="Red" />
        <Setter Property="Rotation" Value="45" />
    </Style>
    
</ResourceDictionary>