Injecting CSS into Webview

XML

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/coordinatorLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    tools:context=".MainActivity"
    android:orientation="vertical"
    >

    <WebView
        android:id="@+id/webView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</LinearLayout>

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JAVA

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import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.DialogInterface;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class WebActivity2 extends AppCompatActivity {

    WebView webView;

    private String style;
    private final static String CREATE_CUSTOM_SHEET =
            "if (typeof(document.head) != 'undefined' && typeof(customSheet) == 'undefined') {"
                    + "var customSheet = (function() {"
                    + "var style = document.createElement(\"style\");"
                    + "style.appendChild(document.createTextNode(\"\"));"
                    + "document.head.appendChild(style);"
                    + "return style.sheet;"
                    + "})();"
                    + "}";
    DisplayMetrics displayMetrics = new DisplayMetrics();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_web2);

//        setTitle("360 degree View Test");
        webView = (WebView) findViewById(R.id.webView);

        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        int height = displayMetrics.heightPixels;
        style= "#wr360PlayerId {"+
                "width: 100%;"+
                "height: 100% !important;"+
                "}";

        showWebPage();
    }



    private void showWebPage(){
        String sURL = "https://www.eichertrucksandbuses.com/360/PRO-6042/exterior/PRO-6042.html";
        webView.setWebViewClient(new MyWebViewClient());
        webView.getSettings().setSupportZoom(true);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setBuiltInZoomControls(true);
        webView.getSettings().setUseWideViewPort(true);
        webView.getSettings().setLoadWithOverviewMode(true);

        webView.loadUrl(sURL);
    }

    private class MyWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
                    injectCssIntoWebView(view, style);
        }

        @Override
        public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
            super.onReceivedError(view, errorCode, description, failingUrl);
            new WebActivity2().showDialog("Oops", "Something went wrong");
        }

    }

    private void showDialog(String title, String msg){
        webView.setVisibility(View.INVISIBLE);
        new AlertDialog.Builder(WebActivity2.this)
            .setTitle(title)
                .setMessage(msg)
                .setCancelable(false)
                .setIcon(android.R.drawable.ic_dialog_alert)
                .setNegativeButton("Retry", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        webView.setVisibility(View.VISIBLE);
                        showWebPage();
                    }
                })
            .setPositiveButton("Back", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    onBackPressed();
                }
            })
            .show();
    }


 private void injectCssIntoWebView(WebView webView, String... cssRules) {
        StringBuilder jsUrl = new StringBuilder("javascript:");
        jsUrl
                .append(CREATE_CUSTOM_SHEET)
                .append("if (typeof(customSheet) != 'undefined') {");
        int cnt = 0;
        for (String cssRule : cssRules) {
            jsUrl
                    .append("customSheet.insertRule('")
                    .append(cssRule)
                    .append("', ")
                    .append(cnt++)
                    .append(");");
        }
        jsUrl.append("}");
        System.out.println("### JS: "+jsUrl.toString());
        webView.loadUrl(jsUrl.toString());
    }


}

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AndroidManifest.xml

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<activity android:name=".WebActivity2"
    android:screenOrientation="landscape"
    android:theme="@style/Theme.AppCompat.NoActionBar"
    />

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