Fix Toolbar color, and semi-transparent window bg.

app/src/main/res/layout/activity_main.xml

@@ -29,6 +29,7 @@
                 android:id="@+id/toolbar"
                 android:layout_width="match_parent"
                 android:layout_height="?attr/actionBarSize"
+                android:background="?attr/colorSurface"
                 app:layout_collapseMode="pin"
                 app:title="@string/app_name"
                 tools:menu="@menu/main_menu" />

app/src/main/res/values/themes.xml

@@ -125,8 +125,8 @@
         <item name="colorPrimaryVariant">@color/purple_600</item>
         <item name="colorSecondary">@color/green_500</item>
         <item name="colorSecondaryVariant">@color/green_200</item>
-        <item name="android:windowBackground">@color/grey_600_a20</item>
-        <item name="android:colorBackground">@color/grey_600_a20</item>
+        <item name="android:windowBackground">@color/grey_900</item>
+        <item name="android:colorBackground">@color/grey_900</item>
         <item name="colorSurface">@color/grey_900</item>
         <item name="colorError">@color/red_200</item>
         <item name="colorOnPrimary">@color/black</item>