styles.xml

<style name="Theme.Themeswitch.Light" parent="android:style/Theme.Light">
    <item name="bigLabel">@style/ShadowedLabel.Light</item>
</style>

<style name="Theme.Themeswitch.Black" parent="android:style/Theme.Black">
    <item name="bigLabel">@style/ShadowedLabel.Black</item>
</style>

<style name="ShadowedLabel">
    <!-- all the common properties -->
    <item name="android:textSize">@dimen/text_size_huge</item>
    <item name="android:textStyle">bold</item>
    <item name="android:shadowDx">1</item>
    <item name="android:shadowDy">1</item>
    <item name="android:shadowRadius">1</item>
</style>

<style name="ShadowedLabel.Black">
    <item name="android:shadowColor">@color/black</item>
</style>

<style name="ShadowedLabel.Light">
    <item name="android:shadowColor">@color/white</item>
</style>