Fix issue #473 - Transparent background

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

@@ -17,6 +17,7 @@
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
+    android:background="?backgroundColor"
     android:layout_height="match_parent">
 
     <androidx.appcompat.widget.AppCompatImageButton