Unable to make toolbar transparent in Android

My tool bar always stays gray when I try to set the background as transparent. Here is my XML.

<android.support.v7.widget.Toolbar xmlns:android="http://ift.tt/nIICcg"
    xmlns:app="http://ift.tt/GEGVYd"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/transparent"
    android:minHeight="@dimen/abc_action_bar_default_height_material"
    app:theme="@style/Rushmore.Toolbar.Transparent" />

And my theme

 <style name="Rushmore.Toolbar.Transparent" parent="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <item name="android:windowActionBarOverlay">true</item>

        <!-- Support Library compability -->
        <item name="windowActionBarOverlay">true</item>
    </style>

I have tried it from code

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);
        toolbar.setBackgroundResource(Color.TRANSPARENT);

I am not sure what is it I am missing...