Importing Styles

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:control="using:AvaloniaApplication"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="AvaloniaApplication.MyUserControl">

    <UserControl.Styles>
        <StyleInclude Source="MyStyles.axaml"></StyleInclude>
    </UserControl.Styles>

    <TextBlock Text="Hello from template" TextAlignment="Center"  Width="200" Height="20"/>

</UserControl>