App.xaml

<maui:MauiWinUIApplication
    x:Class="MauiBlazorUIBestPractices.WinUI.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:maui="using:Microsoft.Maui"
    xmlns:local="using:MauiBlazorUIBestPractices.WinUI">
    <maui:MauiWinUIApplication.Resources>
        <ResourceDictionary>
            <SolidColorBrush x:Key="WindowCaptionForeground">#ffffff</SolidColorBrush>
            <SolidColorBrush x:Key="WindowCaptionBackground">#04173D</SolidColorBrush>
            <SolidColorBrush x:Key="WindowCaptionForegroundDisabled">#ffffff</SolidColorBrush>
            <SolidColorBrush x:Key="WindowCaptionBackgroundDisabled">#04173D</SolidColorBrush>
        </ResourceDictionary>
    </maui:MauiWinUIApplication.Resources>
</maui:MauiWinUIApplication>