iOS 11.1.2上的Xamarin.Forms：Webview加载了更大的字体

我在iOS上没有任何自定义渲染.

这是iPhone 6 iOS 11.1.2上的safari上加载的网站

这里加载在webview上

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/scheR_390_11845@as/2014/forms"
             xmlns:x="http://scheR_390_11845@as.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:Juppie"
             x:Class="Juppie.MainPage">
             <Grid>

    <WebView x:Name="Navegador" source="http://empLeosapp.caonainteractive.com/" 
    Widthrequest="1000" Heightrequest="1000" IsVisible="{Binding Path=HayInternet}" ></WebView>
    <ActivityInDicator IsRunning="{Binding Path=Navegando}" IsVisible="{Binding Path=Navegando}"
        VerticalOptions="CenterAndExpand"
                               HorizontalOptions="CenterAndExpand"
                               RelativeLayout.XConsTraint="{ConsTraintexpression Type=RelativeToParent,Property=Height,Factor=0.33}"
                               RelativeLayout.YConsTraint="{ConsTraintexpression Type=RelativeToParent,Factor=0.33}"/>
    </Grid>


</ContentPage>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Plugin.Connectivity;
using System.ComponentModel;

namespace Juppie
{
    public partial class MainPage : ContentPage,INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public MainPage()
        {
            InitializeComponent();

            Navegador.NavigaTing += Navegador_NavigaTing;
            Navegador.Navigated += (sender,E) => { Navegando = false; };
            HayInternet = true;
            BindingContext = this;
        }
        bool hayInternet;

        public bool HayInternet
        {
            get
            {
                return hayInternet;
            }

            set
            {
                hayInternet = value;

                PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("HayInternet"));

                EvaluarInternet();
            }
        }
        bool navegando;

        public bool Navegando
        {
            get
            {
                return navegando;
            }

            set
            {
                navegando = value;
                PropertyChanged?.Invoke(this,new PropertyChangedEventArgs("Navegando"));

            }
        }

        public async void EvaluarInternet(){
            if (!HayInternet)
            {
             await DisplayAlert("Aviso","Se requiere conexion a internet para emplear esta aplicacion","OK");
            }
        }

        protected override void OnAppearing()
        {
            HayInternet = CrossConnectivity.IsSupported && CrossConnectivity.Current.IsConnected;

            CrossConnectivity.Current.ConnectivityChanged += (sender,args) =>
            {
                HayInternet = args.IsConnected;
            };

            base.onAppearing();
        }

        protected override bool OnBACkButtonPressed()
        {
            if (Navegador.CanGoBACk)
            {
                Navegador.GoBACk();
                return false;
            }

            return base.onBACkButtonPressed();
        }

        void Navegador_NavigaTing(object sender,WebNavigaTingEventArgs E)
        {
            Navegando = true;
            if (e.Url.Contains("/bAnner"))
            {
                e.Cancel = true;

                var uri = new Uri(e.Url.@R_944_9363@ce("/bAnner",""));
                Device.openUri(uri);
            }
        }
    }
}

我尝试使用自定义渲染并设置scalePageToFit = false,但没有成功.
如果有人知道我该如何解决这个问题,请告诉我.