set toolbar background

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

@@ -4,18 +4,21 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context="com.example.paktalin.lavina.MainActivity">
+    tools:context="com.example.paktalin.lavina.MainActivity"
+    android:background="@drawable/red_background">
 
     <android.support.design.widget.AppBarLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:theme="@style/AppTheme.AppBarOverlay">
+        android:theme="@style/AppTheme.AppBarOverlay"
+        android:background="@android:color/transparent"
+        >
 
         <android.support.v7.widget.Toolbar
             android:id="@+id/toolbar"
             android:layout_width="match_parent"
             android:layout_height="?attr/actionBarSize"
-            android:background="?attr/colorPrimary"
+            android:background="@android:color/transparent"
             app:popupTheme="@style/AppTheme.PopupOverlay" />
 
     </android.support.design.widget.AppBarLayout>

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

@@ -8,7 +8,8 @@
     app:layout_behavior="@string/appbar_scrolling_view_behavior"
     tools:context="com.example.paktalin.lavina.MainActivity"
     tools:showIn="@layout/app_bar_main"
-    android:background="@drawable/red_background">
+    android:background="@android:color/transparent"
+    style="@style/AppTheme.PopupOverlay">
 
     <LinearLayout
         android:id="@+id/tabs"