vStationURM/Tools/SonopostSearchTool/App.xaml

<Application x:Class="SonopostSearchTool.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:SonopostSearchTool"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Resources/Language/Chinese.xaml"/>
            </ResourceDictionary.MergedDictionaries>
            
            <SolidColorBrush x:Key="MainTheme" Color="#2C3444"></SolidColorBrush>
        </ResourceDictionary>
    </Application.Resources>
</Application>