ProgressBackgroundColor has weird offset on Kitkat

[philipphager]

Hey,
when I try to use this library, the ProgressBackgroundColor is drawn with an offset above the actual SeekBar.

Code

<app.minimize.com.seek_bar_compat.SeekBarCompat
            android:id="@+id/seekBar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"
            android:max="100"
            app:progressColor="@color/green"
            app:progressBackgroundColor="@color/white"
            app:thumbColor="@color/green"/>

API 19