make bottom sheets' background white

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

@@ -24,7 +24,7 @@
                                                      android:id="@+id/bottom_sheet"
                                                      android:layout_width="match_parent"
                                                      android:layout_height="wrap_content"
-                                                     android:background="?android:attr/windowBackground"
+                                                     android:background="@color/white"
                                                      app:layout_behavior="@string/appbar_scrolling_view_behavior">
 
 

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

@@ -20,5 +20,5 @@
         android:layout_height="wrap_content"
         android:layout_gravity="bottom"
         android:animateLayoutChanges="true"
-        android:background="?android:attr/windowBackground"/>
+        android:background="@color/white"/>
 </android.support.design.widget.CoordinatorLayout>