title: Notification background in Android Lollipop is white. How can I change it?
body: <p>I want to show a notification for a message in my app. In previous versions of Android everything is ok, but in Lollipop the notification background is white. 
  I used this XML code for my notification layout in <code>layout_message_notification.xml</code>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:id="@+id/layout_messageNotification"
      android:orientation="horizontal"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:background="@android:color/transparent"&gt;
  
      &lt;LinearLayout
          android:layout_width="0dp"
          android:layout_weight=".2"
          android:layout_height="wrap_content"
          android:background="@android:color/transparent"&gt;
  
          &lt;ImageView
              android:layout_width="fill_parent"
              android:layout_height="wrap_content"
              android:scaleType="fitCenter"
              android:src="@drawable/message_icon"/&gt;
  
      &lt;/LinearLayout&gt;
  
      &lt;LinearLayout
          android:layout_width="0dp"
          android:layout_weight=".8"
          android:layout_height="wrap_content"
          android:background="@android:color/transparent"&gt;
  
          &lt;TextView
              android:id="@+id/textView_notification_title"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
              android:gravity="right|center_vertical"
              android:layout_margin="15dp"/&gt;
  
      &lt;/LinearLayout&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>My notification in lollipop is shown like this: 
  <img src="https://i.stack.imgur.com/5lRJY.png" alt="notification style in lollipop"></p>
  
  <p>How can I make the notification background dark or transparent, like in previous versions of Android?</p>