how to set all window background color in kotlin xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/yourBackgroundColor">

    <!-- Your UI components go here -->

</RelativeLayout>

In your res/values/colors.xml file:

<resources>
    <color name="yourBackgroundColor">#FF0000</color>
</resources>