templates/activities/FullscreenActivity/root/res/values/styles.xml

<resources>

    <style name="FullscreenTheme" parent="android:Theme.NoTitleBar">
        <item name="android:windowContentOverlay">@null</item>
        <item name="android:windowBackground">@null</item>
        <item name="buttonBarStyle">@style/ButtonBar</item>
        <item name="buttonBarButtonStyle">@style/ButtonBarButton</item>
    </style>

    <!-- Backward-compatible version of ?android:attr/buttonBarStyle -->
    <style name="ButtonBar">
        <item name="android:paddingLeft">2dp</item>
        <item name="android:paddingTop">5dp</item>
        <item name="android:paddingRight">2dp</item>
        <item name="android:paddingBottom">0dp</item>
        <item name="android:background">@android:drawable/bottom_bar</item>
    </style>

    <!-- Backward-compatible version of ?android:attr/buttonBarButtonStyle -->
    <style name="ButtonBarButton" />

</resources>