How to style the divider between Ice Cream Sandwich tabs?

After removing every style I use I got the following image:

This image also contains the small gaps. Therefore it seems that this is some kind of default behavior.

However I found a way to work around the problem. I set the redline as a standard Background for the whole tabbar. This way the gap appears but nobody can see it because the background, that already contains the line is shown.

I now use the following style for all my activities:

<style name="LightThemeSelector" parent="android:Theme.Holo.Light">
    <item name="android:actionBarTabBarStyle">@style/customTabBar</item>
    <item name="android:actionBarTabStyle">@style/customTabStyle</item>
</style>

This style is used to style each single tab inside the tabbar:

<style name="customTabStyle" parent="@android:style/Widget.Holo.ActionBar.TabView">
    <item name="android:showDividers">none</item>
    <item name="android:measureWithLargestChild">true</item>
    <item name="android:background">@drawable/tab_line</item>
    <item name="android:gravity">center</item>
</style>

To style the whole Tabbar i use the following style:

<style name="customTabBar" parent="@android:style/Widget.Holo.ActionBar.TabBar">
    <item name="android:showDividers">middle</item>
    <item name="android:divider">@drawable/divider</item>
    <item name="android:dividerPadding">0dp</item>
    <item name="android:background">@drawable/tab_unselected</item>
</style>

This style defines my custom divider and also defines the background for the tabbar. As background I directly set the nine patch drawable that is drawn if a tab is not selected.
The result of all this is a tabbar with a red underline without any gaps.