How can I reduce the width of Master Detail page?

this is my code

<?xml version="1.0" encoding="utf-8" ?>

<MasterDetailPage.Master>

    <ContentPage Title="Menu" Icon="hamburger.png"
             BackgroundColor="Red" 
                  >

        <StackLayout Orientation="Vertical" >
            <ListView x:Name="navigationDrawerList"  
              RowHeight="55"
              SeparatorVisibility="None"
              ItemTapped="navigationDrawerList_ItemTapped"
              BackgroundColor="White">

                <ListView.Header>
                    <Grid HorizontalOptions="FillAndExpand"
                        VerticalOptions="FillAndExpand">


                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*"/>
                            <ColumnDefinition Width="Auto"/>
                            <ColumnDefinition Width="*"/>
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="30"/>
                            <RowDefinition Height="80"/>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>

                        </Grid.RowDefinitions>
                        <Image Source="LogoTienditaDel2000.jpg"                              
                            Aspect="AspectFit"
                            Grid.RowSpan="5"
                            Grid.ColumnSpan="4"
                            HorizontalOptions="FillAndExpand" 
                            VerticalOptions="FillAndExpand">
                        </Image>

                        <controls:CircleImage
                            Margin="10,0,0,0"
                        Source="user.jpg"
                        Grid.ColumnSpan="4"
                        Grid.Row="1"
                        HorizontalOptions="Start"
                        VerticalOptions="End"/>
                    </Grid>
                </ListView.Header>


                <ListView.ItemTemplate>
                    <DataTemplate>
                        <customControls:ExtendedViewCell SelectedBackgroundColor="White">
                            <ViewCell.View>

                                <StackLayout 
                                    VerticalOptions="FillAndExpand"  
                                    Orientation="Horizontal"  
                                    Padding="20,10,0,10"  
                                    Spacing="20">
                                    <Image Source="{Binding Icon}"  
                                        WidthRequest="30"  
                                        HeightRequest="30"  
                                        VerticalOptions="Center" />
                                    <Label Text="{Binding Title}"  
                                        FontSize="Medium"  
                                        VerticalOptions="Center"  
                                        TextColor="Black"/>

                                </StackLayout>

                            </ViewCell.View>
                        </customControls:ExtendedViewCell>
                    </DataTemplate>
                </ListView.ItemTemplate>

            </ListView>

        </StackLayout>

    </ContentPage>
</MasterDetailPage.Master>

<MasterDetailPage.Detail >
    <NavigationPage>

    </NavigationPage>
</MasterDetailPage.Detail>