<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="20dp"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <Button
        android:id="@+id/dark"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="20.dp"
        android:text="Dark theme" />

    <Button
        android:id="@+id/light"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Light Theme" />
</LinearLayout>

  // Changing Themes using Buttons !

        val buttonDark = findViewById<Button>(R.id.dark)
        val buttonLight = findViewById<Button>(R.id.light)
        val layout = findViewById<LinearLayout>(R.id.main)

        buttonDark.setOnClickListener {
            layout.setBackgroundResource(R.color.black)
        }

        buttonLight.setOnClickListener {
            layout.setBackgroundResource(R.color.white)
        }