title: how to make tool bar transparent
body: <p>I want to make my toolbar transparent but don't know how?
     `</p>
  
  <pre><code> &lt;?xml version="1.0" encoding="utf-8"?&gt;
    &lt;android.support.v7.widget.Toolbar
       xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      app:theme="@style/TransparentToolbar"
      android:background="@android:color/transparent"&gt;
    &lt;/android.support.v7.widget.Toolbar&gt;
  </code></pre>