I set the backgound color of my app ‘light’ but in my emulator it shows dark, the backgound not applied properly

the background defined is white but the theme is still dark please help me!

<?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:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:backgroundTint="#dfdfdf"
    android:orientation="vertical"
    app:circularflow_radiusInDP="50dp"
    tools:context=".MainActivity">

    <Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/design_default_color_primary_dark"
        android:gravity="end"
        android:textAlignment="textEnd"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        android:title="Fit & Flex"
        android:titleTextColor="#FFF" />

that’s the code but output is :