Android support-v7 CardView: Header textview with other background color does not extend until the edges

Question

I want to create a layout with a CardView, which contains a header with an other background color, similar to what is shown in the current Google Now screen (See below).

The darker colored header (containing the text "iPhone 6") extends completely towards the edges and rounded corners of the CardView.

I tried to build a similar CardView with the support-v7 library (android.support.v7.widget.CardView).

Screenshot below.

In my case, the blue background color of the header however, does not fully extend towards the edges of my CardView. There is a small white border (the background color of the CardView) visible at the left, upper and right edges. This seems to be a consequence of the rounded corners of the CardView.

How can I get the background color of my header (a TextView), to extend completely towards the edges and rounded corners of my CardView?

This is the relevant part of my xml layout file:

<android.support.v7.widget.CardView
        android:id="@+id/calendar_detail_time_card"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/calendar_detail_title_card"
        android:layout_margin="6dp"
        card_view:cardCornerRadius="3dp"
        card_view:cardUseCompatPadding="true">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textColor="@color/white"
                android:background="@color/primaryColor"
                android:padding="8dp"
                android:textSize="@dimen/calendar_detail_large"
                android:textStyle="bold"
                android:id="@+id/header_when"
                android:text="@string/header_when"
                tools:text="When?"/>

            <ImageButton
                android:id="@+id/calendar_detail_add_to_calendar_button"
                style="?android:borderlessButtonStyle"
                android:layout_width="@dimen/calendar_detail_add_to_calendar_image"
                android:layout_height="@dimen/calendar_detail_add_to_calendar_image"
                android:layout_alignParentRight="true"
                android:layout_alignParentTop="true"
                android:src="@drawable/ic_calendar_red" />

            <TextView
                android:id="@+id/calendar_detail_time"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/header_when"
                android:padding="8dp"
                tools:text="Time" />

        </RelativeLayout>

    </android.support.v7.widget.CardView>

Answer 1

Add this code to your card in xml:

card_view:cardPreventCornerOverlap="false"

And now it will extend all the way.