card.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle"
            android:dither="true">
            <corners android:radius="2dp"/>
            <solid android:color="#CCC" />
        </shape>
    </item>
    <item android:bottom="2dp">
        <shape android:shape="rectangle"
            android:dither="true">
            <corners android:radius="2dp" />
            <solid android:color="#FFF" />
            <padding android:bottom="6dp"
                android:left="4dp"
                android:right="4dp"
                android:top="4dp" />
        </shape>
    </item>
</layer-list>

card_button.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/card_pressed" android:state_activated="true"/>
    <item android:drawable="@drawable/card_pressed" android:state_checked="true"/>
    <item android:drawable="@drawable/card_pressed" android:state_selected="true"/>
    <item android:drawable="@drawable/card_pressed" android:state_pressed="true"/>
    <item android:drawable="@drawable/card_pressed" android:state_active="true"/>
    <item android:drawable="@drawable/card"/>
</selector>

card_pressed.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle"
            android:dither="true">
            <corners android:radius="2dp"/>
            <solid android:color="#CCC" />
        </shape>
    </item>
    <item android:bottom="2dp">
        <shape android:shape="rectangle"
            android:dither="true">
            <corners android:radius="2dp" />
            <solid android:color="#22000000" />
            <padding android:bottom="6dp"
                android:left="4dp"
                android:right="4dp"
                android:top="4dp" />
        </shape>
    </item>
</layer-list>