gecko/mobile/android/base/resources/drawable/home_panel_title_background.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:left="-1dp"
          android:right="-1dp"
          android:top="-1dp">

        <shape android:shape="rectangle" >
            <stroke android:width="1px"
                    android:color="@color/doorhanger_divider_light" />

            <solid android:color="#00000000" />
        </shape>
    </item>

</layer-list>