Android CardView with rounded corners displays grey corners : <p>I'm inflating a custom layout with CardView inside the layout. 
The rounded corners are displayed as expected but I also get grey background behind the corners.</p>

<p>The code is simple, uses a CardView with corner radius and a background color. 
I've tried setting transparent background but doesn't work. However, if i set another opaque color, it is displayed in corners.</p>

<p>Code is attached.</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/transparent"&gt;

    &lt;android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:cardBackgroundColor="@android:color/white"
        app:cardCornerRadius="6dp"
        app:cardElevation="5dp"&gt;

        &lt;RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@android:color/transparent"&gt;

            &lt;TextView
                android:id="@+id/tvProgress"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentLeft="true"
                android:layout_alignParentStart="true"
                android:layout_centerVertical="true"
                android:layout_toLeftOf="@+id/ivIcon"
                android:layout_toStartOf="@+id/ivIcon"
                android:background="@android:color/transparent"
                android:padding="@dimen/elementPaddingSmall"
                android:text="Initial Discussion"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textColor="@android:color/black" /&gt;

            &lt;ImageView
                android:id="@+id/ivIcon"
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:layout_alignParentEnd="true"
                android:layout_alignParentRight="true"
                android:background="@color/lightBrown"
                android:scaleType="centerInside"
                android:src="@drawable/ic_checkmark_circle" /&gt;
        &lt;/RelativeLayout&gt;


    &lt;/android.support.v7.widget.CardView&gt;
&lt;/RelativeLayout&gt;
</code></pre>

<p>Result:</p>

<p><a href="https://i.stack.imgur.com/FqNBa.png" rel="noreferrer"><img src="https://i.stack.imgur.com/FqNBa.png" alt="enter image description here"></a></p>
