created background_light.xml:
`

<gradient
    android:angle="270"
    android:endColor="@color/clr_theme_indigo"
    android:startColor="@color/clr_dashboard_toolbar"
    android:type="linear" />

`
background_dark.xml

`<?xml version="1.0" encoding="UTF-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <gradient
        android:angle="270"
        android:endColor="@color/black"
        android:startColor="@color/black"
        android:type="linear" />

    <corners
        android:bottomLeftRadius="@dimen/_5sdp"
        android:bottomRightRadius="@dimen/_5sdp" />
</shape>`

How to combine both the xml file apply activity_main.xml:

android:background=”@drawable/background”
like this