Dark mode xml file

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/background_lay"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/mode_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/button_design"
        android:paddingLeft="50dp"
        android:paddingRight="50dp"
        android:text="@string/mode"
        android:textColor="@color/button_text"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>