浏览器控件未显示整个页面

我想知道为什么我第一次尝试用WebBrowser加载信息时，页面被裁剪了，而第二次却很好地显示了信息。

或者，例如，方向为纵向，当我转到横向并返回人像时，将显示所有内容

这是我使用的代码。

private void Default_Loaded(object sender, RoutedEventArgs e)
    {
        //  Only need to reset web page when creating a new info page (coming from Info index or tombstoned app):
        if (_newPageInstance && (NavigationContext.QueryString.Count >= 1))
        {
            //  Set html page for web browser control based on park and page # passed in:
            if (_parkId.Length <= 0)
            {
                _parkId = App.MapModel.InfoParkId;  //  App.ViewModel.CurrentPark.ParkId might not be ready if tombstoned
                _parkPage = Convert.ToInt32(NavigationContext.QueryString.Values.First());
                SubTitle.Text = App.MapModel.InfoPageTitle; //  set title like "Legend" for this page
            }
            //  else - these 3 values were set during OnNavigatedTo when returning from tombstoning
            //
            Browser.Base = Constants.ParkInfoDirectory;    //  "ParkInfo" folder
            string s = string.Format("{0}/section_{1}.html", _parkId, _parkPage);    //  URL = "/ParkInfo/ti217/5" for page 5 of Rainier
            Browser.Navigate(new Uri(s, UriKind.Relative));
            //Browser.Navigate(new Uri(s, UriKind.Relative));
        }
        //var myHeight = this.ActualHeight;
        //Browser.Height = ((StackPanel)Browser.Parent).ActualHeight;
        this.Browser.UpdateLayout();
        this.ContentPanel.UpdateLayout();
    }
    // Executes when the user navigates to this page (or coming back from being tombstoned):
    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        base.OnNavigatedTo(e);
        if (ParkMaps.App.ViewModel.CurrentPark != null)
        {
            //  Set title bar to use this park's name:
            PageTitle.Text = ParkMaps.App.ViewModel.CurrentPark.ParkNameUpper;
        }
        else PageTitle.Text = "Park Maps";
        // If the constructor has been called AND the PreservingPageState key is in the State dictionary,
        // then the UI state for this page should be restored:
        if (_newPageInstance && this.State.ContainsKey("PreservingPageState"))
        {
            //  Restore the state of the UI:
            try
            {
                _parkId = Utilities.TryGetValue<string>(State, "InfoParkId", "ti217");
                _parkPage = Utilities.TryGetValue<int>(State, "InfoDetailsParkPage", 0);
                SubTitle.Text = Utilities.TryGetValue<string>(State, "InfoDetailsSubtitle", "Park Info");
                //  NOTE: Browser not ready yet, so load web page in Default_Loaded above
            }
            catch { } //  Don't restore anything if had trouble above
        }
    }

这是XAML

    <StackPanel Orientation="Vertical"  Grid.Row="0">
        <StackPanel x:Name="TitlePanel" Margin="8,4,8,4" Orientation="Horizontal">
            <Image Source="{Binding LogoImageSource}" ManipulationCompleted="LogoBar_ManipulationCompleted" Width="208" Stretch="Uniform" HorizontalAlignment="Left" Margin="9,0,0,0"/>
            <TextBlock x:Name="PageTitle" Text="Park Maps" ManipulationCompleted="LogoBar_ManipulationCompleted" Width="250" Margin="-8,4,0,4" Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="NoWrap" TextAlignment="Right" HorizontalAlignment="Stretch" />
        </StackPanel>
        <TextBlock x:Name="SubTitle" Text="Legend" Margin="9,6,9,9" Style="{StaticResource PhoneTextLargeStyle}" TextWrapping="Wrap" TextAlignment="Center" />
    </StackPanel>

    <!--ContentPanel - place additional content here-->
    <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0" MinHeight="697" VerticalAlignment="Stretch" >

    </Grid>
</Grid>

 Stretch="Fill"