修改主題為「Light」

App.xaml

<Application
    x:Class="App2.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App2"
    RequestedTheme="Light">

    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>

                <!-- 
                    定義平台外觀及操作之通用層面的樣式
                    Visual Studio 專案及項目範本的必要項
                 -->
                <ResourceDictionary Source="Common/StandardStyles.xaml"/>
            </ResourceDictionary.MergedDictionaries>

        </ResourceDictionary>
    </Application.Resources>
</Application>