Home Page Background Image not showing in Android Webview App

Question

Here is some screenshot of and app and a website. Please see them first.

Website in mobile view is not showing any problems, but in the app home page first background image not showing. Website Screenshot

App Screenshot

Android Webview app using Java

AndroidManifest.xml File

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.fencydroid.multibally">

     <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MultiballyApp">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

MainActivity.java File Below...

    @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
           // Hide Title ber
            requestWindowFeature(Window.FEATURE_NO_TITLE);
            this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
            getSupportActionBar().hide();
            // Hide Title ber  End
            setContentView(R.layout.activity_main);
            String url = "https://www.domainname.com";
            WebView = findViewById(R.id.web);
            WebView.loadUrl(url);
            WebView.getSettings().setJavaScriptEnabled(true);
            WebView.getSettings().setBuiltInZoomControls(false);
            WebView.setWebViewClient(new WebViewClient());
            //Rate System
            AppRate.with(this)
                    .setInstallDays(0)
                    .setLaunchTimes(3)
                    .setRemindInterval(2)
                    .monitor();
            AppRate.showRateDialogIfMeetsConditions(this);
            //Rate System end
        }
    
        @Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            if (event.getAction() == KeyEvent.ACTION_DOWN) {
                switch (keyCode) {
                    case KeyEvent.KEYCODE_BACK:
                        if (WebView.canGoBack()) {
                            WebView.goBack();
                        } else {
                            finish();
                        }
                        return true;
                }
    
            }
            return super.onKeyDown(keyCode, event);
        }}

Answer 1

等待大神答复