Remove toolbar top shadow

edit.xml

// Remove toolbar top shadow
// Base code is android studio new application template
// AndroidManifest.xml
  <activity
    android:name=".MainActivity"
    android:label="@string/app_name"
-   android:theme="@style/AppTheme.NoActionBar"> // Remove this line
+   android:theme="@style/AppTheme"> // Replace this line
  
// styles.xml
<!-- Base application theme. -->
-   <style name="AppTheme" parent="Theme.AppCompat.Light">
+   <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
      <!-- Customize your theme here. -->
      <item name="colorPrimary">@color/colorPrimary</item>
      <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
      <item name="colorAccent">@color/colorAccent</item>
      <item name="android:windowBackground">@color/colorWhiteBackground</item>
    </style>
  
-   <style name="AppTheme.NoActionBar">
-     <item name="windowActionBar">false</item>
-     <item name="windowNoTitle">true</item>
-   </style>