App.xaml

<Application x:Class="Caliber.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:Caliber"
             xmlns:md="http://materialdesigninxaml.net/winfx/xaml/themes" 
             StartupUri="View\MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <local:VMLoader x:Key="VMLoader"/>
            <ResourceDictionary.MergedDictionaries>
                <md:BundledTheme BaseTheme="Dark"
                                 PrimaryColor="Indigo"
                                 SecondaryColor="Yellow" />
                <ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.Wpf;component/Themes/MaterialDesignTheme.Defaults.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>