How to customize spinner

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="240dp"
        android:layout_height="wrap_content"
        android:background="@color/blue"
        android:minHeight="48dp"
        android:paddingEnd="10dp" />

</LinearLayout>