WPF修改窗体标题栏的颜色

<Fluent:RibbonWindow x:Class="WpfDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:Fluent="urn:fluent-ribbon"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfDemo"
        mc:Ignorable="d" Background="green" Title="MainWindows"
        Height="350" Width="525">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

        <Grid Grid.Row="1">
            <TextBlock>My first window containing a Ribbon and something else.</TextBlock>
        </Grid>
    </Grid>
</Fluent:RibbonWindow>

using System.Windows;

namespace WpfDemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Fluent.RibbonWindow
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}