XML : Toolbar not getting transparent background even after declaring it in xml. Please see details

I want a transparent Toolbar for which I have declared the android:background="@android:color/transparent" attribute.

The problem is that the Toolbar is still having the background color set as my colorPrimary which is #00BCD4.

Here's activity_login_screen.xml file's code:

  <?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.abc.xyz.LoginScreen">        <android.support.design.widget.AppBarLayout          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:theme="@style/AppTheme.AppBarOverlay">            // here is the toolbar.          <android.support.v7.widget.Toolbar              android:id="@+id/toolbar"              android:layout_width="match_parent"              android:layout_height="?attr/actionBarSize"              android:background="@android:color/transparent"              app:popupTheme="@style/AppTheme.PopupOverlay"/>        </android.support.design.widget.AppBarLayout>        <include layout="@layout/content_login_screen"/>    </android.support.design.widget.CoordinatorLayout>    

Here's LoginScreen.java file's code:

  public class LoginScreen extends AppCompatActivity {        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_login_screen);          Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);          toolbar.setBackgroundColor(Color.alpha(0));          setSupportActionBar(toolbar);          getSupportActionBar().setDisplayHomeAsUpEnabled(true);            TextView textView = (TextView) findViewById(R.id.text);          Typeface typeface = Typeface.createFromAsset(getBaseContext().getAssets(), "fonts/Pacifico.ttf");          textView.setTypeface(typeface;        }    }    

Here's styles.xml file's code:

  <resources>        <!-- Base application theme. -->      <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">          <!-- Customize your theme here. -->          <item name="colorPrimary">@color/colorPrimary</item>          <item name="colorPrimaryDark">@color/colorPrimaryDark</item>          <item name="colorAccent">@color/colorAccent</item>          <item name="colorControlHighlight">@color/colorControlHighlight</item>      </style>        <style name="AppTheme.NoActionBar">          <item name="windowActionBar">false</item>          <item name="windowNoTitle">true</item>      </style>        <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar"/>        <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light"/>    </resources>    

Please let me know what is wrong here. Why the Toolbar is not getting transparent background??

Thanks in advance.