MainActivity.kt

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setTheme(R.style.AppTheme)
        val systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_STABLE or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
        window.decorView.systemUiVisibility = systemUiVisibility

        setContentView(R.layout.activity_main)

        someBottomView.doOnApplyWindowInsets { view, windowInsets, initialPadding ->
            view.setPadding(
                initialPadding.left,
                initialPadding.top,
                initialPadding.right,
                initialPadding.bottom + windowInsets.systemWindowInsetBottom
            )
        }
    }

styles.xml

    <style name="AppTheme" parent="AppTheme.Base">
        <item name="android:windowTranslucentStatus">false</item>
        <item name="android:windowTranslucentNavigation">false</item>
        <item name="android:windowDrawsSystemBarBackgrounds">true</item>
        <item name="android:statusBarColor">@android:color/transparent</item>
        <item name="android:navigationBarColor">@android:color/transparent</item>
    </style>

ViewExt.kt

fun View.requestApplyInsetsWhenAttached() {
    if (isAttachedToWindow) {
        // We're already attached, just request as normal
        requestApplyInsets()
    } else {
        // We're not attached to the hierarchy, add a listener to
        // request when we are
        addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {
            override fun onViewAttachedToWindow(v: View) {
                v.removeOnAttachStateChangeListener(this)
                v.requestApplyInsets()
            }

            override fun onViewDetachedFromWindow(v: View) = Unit
        })
    }
}

fun View.doOnApplyWindowInsets(f: (View, WindowInsets, InitialPadding) -> Unit) {
    // Create a snapshot of the view's padding state
    val initialPadding = recordInitialPaddingForView(this)
    // Set an actual OnApplyWindowInsetsListener which proxies to the given
    // lambda, also passing in the original padding state
    setOnApplyWindowInsetsListener { v, insets ->
        f(v, insets, initialPadding)
        // Always return the insets, so that children can also use them
        insets
    }
    // request some insets
    requestApplyInsetsWhenAttached()
}

data class InitialPadding(
    val left: Int, val top: Int,
    val right: Int, val bottom: Int
)

private fun recordInitialPaddingForView(view: View) = InitialPadding(
    view.paddingLeft, view.paddingTop, view.paddingRight, view.paddingBottom
)