You have to override the style of the action bar. You can change as your requirement.
<style name="CustomActionBarTheme"
parent="@android:style/Theme.Holo.Light.DarkActionBar">
<item name="android:actionBarTabTextStyle">@style/TabTextStyle</item>
<item name="actionBarTabTextStyle">@style/TabTextStyle</item>
<item name="android:scrollHorizontally">false</item>
<item name="android:paddingLeft">0dp</item>
<item name="android:paddingRight">0dp</item>
</style>
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