title: Android CardView with weird border when transparent
body: <p>I'm having some trouble with CardView transparency and card_elevation. Trying to use a CardView transparent the result is:</p>
  
  <p><a href="https://i.stack.imgur.com/YGIk3.png" rel="noreferrer"><img src="https://i.stack.imgur.com/YGIk3.png" alt="enter image description here"></a></p>
  
  <p>Without transparency:</p>
  
  <p><a href="https://i.stack.imgur.com/39pvu.png" rel="noreferrer"><img src="https://i.stack.imgur.com/39pvu.png" alt="enter image description here"></a></p>
  
  <p>What I'm trying to get is something like this:</p>
  
  <p><a href="https://i.stack.imgur.com/gScrz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/gScrz.png" alt="enter image description here"></a></p>
  
  <p>Here is my xml:</p>
  
  <pre><code>&lt;RelativeLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:card_view="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:background="@mipmap/eifell"
      android:padding="10dp"
      tools:context=".MainActivity"&gt;
  
      &lt;ScrollView
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:paddingTop="5dp"
          android:background="@android:color/transparent"&gt;
  
          &lt;LinearLayout
              android:layout_width="match_parent"
              android:layout_height="wrap_content"&gt;
  
              &lt;android.support.v7.widget.CardView
                  android:id="@+id/newsCardView"
                  android:layout_width="match_parent"
                  android:layout_height="175dp"
                  card_view:cardBackgroundColor="#602B608A"
                  card_view:cardElevation="5dp"&gt;
  
                  &lt;LinearLayout
                      android:layout_width="match_parent"
                      android:layout_height="match_parent"
                      android:background="@android:color/transparent"&gt;
                  &lt;/LinearLayout&gt;
  
              &lt;/android.support.v7.widget.CardView&gt;
  
          &lt;/LinearLayout&gt;
      &lt;/ScrollView&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>