<resources>

    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    </style>

    <style name="BeatBoxButton">
        <item name="android:background">@color/dark_blue</item>
    </style>
</resources>

<resources>

    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    </style>

    <style name="BeatBoxButton">
        <item name="android:background">@color/dark_blue</item>
    </style>

    <style name="BeatBoxButton.Strong">
        <item name="android:textStyle">bold</item>
    </style>

</resources>

Define new style BeatBoxButton.Strong that inherit from BeatBoxButton
Define new style BeatBoxButton.Strong that inherit from BeatBoxButton
