App.xaml

<Application x:Class="FastFood.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:FastFood"
             StartupUri="LoginWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Themes/LightTheme.xaml" />
                <!--end::Themes-->

                <!--begin::Icons-->
                <ResourceDictionary Source="/Assets/Icons/Icons.xaml"/>
                <!--end::Icons-->

                <!--begin::Styles-->
                <ResourceDictionary Source="/Styles/ButtonStyles.xaml"/>
                <ResourceDictionary Source="/Styles/ComboBoxStyles.xaml"/>
                <ResourceDictionary Source="/Styles/DateTimePickerStyles.xaml"/>
                <!--end::Styles-->
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>