XML : NestedScrollview doesnot hide Toolbar properly

i am using webview inside NestedScrollView which allows me to hide and show toolbar on scroll but there is an issue. the title from toolbar and hamburger is visible Image<>

here is the main view code

  <?xml version="1.0" encoding="utf-8"?>  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:app="http://schemas.android.com/apk/res-auto"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:layout_marginTop="0dp"  app:layout_behavior="@string/appbar_scrolling_view_behavior">            <ProgressBar              android:id="@+id/progressbar_Horizontal"              style="?android:attr/progressBarStyleHorizontal"              android:layout_width="match_parent"              android:layout_height="10dp"              android:layout_alignParentLeft="true"              android:layout_alignParentStart="true"              android:layout_alignParentTop="true"              android:indeterminate="true"              android:indeterminateTint="@color/header_back_ground"              android:max="100" />            <android.support.v4.widget.SwipeRefreshLayout              android:id="@+id/swipe_refresh"              android:layout_width="match_parent"              android:layout_height="match_parent"              android:layout_below="@+id/progressbar_Horizontal">                <android.support.v4.widget.NestedScrollView                  android:layout_width="match_parent"                  android:layout_height="match_parent"                  android:id="@+id/nested_scroll_view"                  android:fitsSystemWindows="true"                  app:layout_behavior="@string/appbar_scrolling_view_behavior">                <WebView                  android:id="@+id/web"                  android:layout_width="match_parent"                  android:layout_height="wrap_content"                  android:layout_centerHorizontal="true" />              </android.support.v4.widget.NestedScrollView>            </android.support.v4.widget.SwipeRefreshLayout>  </RelativeLayout>    

And here is the code from app_bar_main

  <?xml version="1.0" encoding="utf-8"?>  <android.support.design.widget.CoordinatorLayout   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:layout_width="match_parent"  android:layout_height="match_parent"  android:fitsSystemWindows="true"  tools:context="com.pressplus.android.demo.MainActivity">    <android.support.design.widget.AppBarLayout      android:id="@+id/app_bar"      android:layout_width="match_parent"      android:layout_height="wrap_content"      android:animateLayoutChanges="true"      android:theme="@style/AppTheme.AppBarOverlay">        <android.support.v7.widget.Toolbar          android:id="@+id/toolbar"          android:layout_width="match_parent"          android:layout_height="?attr/actionBarSize"          android:background="?attr/colorPrimary"          app:layout_scrollFlags="scroll|enterAlways"          app:popupTheme="@style/AppTheme.PopupOverlay"/>    </android.support.design.widget.AppBarLayout>    <include layout="@layout/press_plus_demo" />    </android.support.design.widget.CoordinatorLayout>