make sure the background is black even at very few directories

app/src/main/java/gallery/simplemobiletools/com/MainActivity.java

@@ -14,6 +14,7 @@ import java.util.Map;
 import java.util.TreeMap;
 
 public class MainActivity extends AppCompatActivity {
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

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

@@ -2,13 +2,13 @@
 <RelativeLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:background="@android:color/black">
 
     <GridView
         android:id="@+id/photo_grid"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:background="@android:color/black"
         android:columnWidth="@dimen/photo_size"
         android:horizontalSpacing="2dp"
         android:numColumns="auto_fit"