...

app/src/main/res/layout/activity_main2.xml

@@ -35,9 +35,9 @@
         app:layout_constraintBottom_toBottomOf="parent">
 
         <androidx.constraintlayout.widget.ConstraintLayout
-
             android:layout_width="match_parent"
             android:layout_height="64dp"
+            android:background="@color/white"
             android:orientation="horizontal">
 
             <LinearLayout