remove margin between spinner items

Question

У меня простой spinner

 vSpinner = new AppCompatSpinner(get_baseField().getContext());
 vSpinner.setBackgroundColor(Color.GREEN);
 vSpinner.setPopupBackgroundDrawable(new ColorDrawable(Color.CYAN));
 vSpinner.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));     

and this is my custom item for spinner

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/item_container_spinner"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:orientation="horizontal"
app:cardUseCompatPadding="true"
app:contentPadding="2dp">

<ir.medium.fwk.ui.CustomTextView
    android:id="@+id/item_txt"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:lines="1"
    android:textColor="@color/text_color_90"
    android:textSize="@dimen/text_size_medium"
    app:fontName="samim.ttf" />

 </android.support.v7.widget.CardView>

и это результат

my problem is this red background color.

why I've seen it?

как я могу удалить это?

I get a inspect from my layout and see the red layout is android.widget.ListPopupWindow$DropDownListView@a9dfd7
кто-нибудь может мне помочь с этим?