Android Coordinator layout problems -

i using coordinator layout custom collapsing view , tablayout. here xml

<android.support.design.widget.coordinatorlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:fresco="http://schemas.android.com/apk/res-auto" android:id="@+id/main_content" android:layout_width="match_parent" android:layout_height="match_parent" android:fitssystemwindows="true">  <android.support.design.widget.appbarlayout     android:id="@+id/appbar"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:theme="@style/themeoverlay.appcompat.light">      <android.support.design.widget.collapsingtoolbarlayout         android:id="@+id/collapsing_toolbar"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:fitssystemwindows="true"         app:contentscrim="?attr/colorprimary"         app:layout_scrollflags="scroll|exituntilcollapsed">          <relativelayout             android:id="@+id/cardparentlayout"             android:layout_width="match_parent"             android:layout_height="match_parent"             app:layout_collapsemode="parallax">              <com.facebook.drawee.view.simpledraweeview                 android:id="@+id/profilepicoverlay"                 android:layout_width="match_parent"                 android:layout_height="match_parent"                 fresco:actualimagescaletype="centercrop"                 fresco:overlayimage="@drawable/profile_overlay" />              <relativelayout                 android:id="@+id/childparenttoanimate"                 android:layout_width="match_parent"                 android:layout_height="match_parent"                 android:visibility="invisible">                  <include                     android:id="@+id/cardlayout"                     layout="@layout/layout_profile_card"                     android:layout_width="match_parent"                     android:layout_height="wrap_content"                     android:layout_centerinparent="true" />                  <com.facebook.drawee.view.simpledraweeview                     android:id="@+id/profilepiccard"                     android:layout_width="wrap_content"                     android:layout_height="wrap_content"                     android:layout_centerhorizontal="true"                     fresco:actualimagescaletype="centercrop"                     fresco:backgroundimage="@drawable/profile_placeholder"                     fresco:roundascircle="true"                     fresco:roundingbordercolor="@color/white"                     fresco:roundingborderwidth="2dp" />              </relativelayout>          </relativelayout>          <android.support.v7.widget.toolbar             android:id="@+id/toolbar"             android:layout_width="match_parent"             android:layout_height="51dp"             app:layout_collapsemode="pin"             app:popuptheme="@style/apptheme" />      </android.support.design.widget.collapsingtoolbarlayout>  </android.support.design.widget.appbarlayout>  <linearlayout     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:layout_gravity="fill_vertical"     android:fillviewport="true"     android:orientation="vertical"     app:layout_behavior="@string/appbar_scrolling_view_behavior">      <android.support.design.widget.tablayout         android:id="@+id/tabs"         android:layout_width="match_parent"         android:layout_height="?attr/actionbarsize"         android:layout_gravity="bottom"         android:background="@color/blue_primary"         app:tabgravity="fill"         app:tabindicatorcolor="@android:color/white"         app:tabmode="fixed" />      <android.support.v4.view.viewpager         android:id="@+id/viewpager"         android:layout_width="match_parent"         android:layout_height="match_parent" />  </linearlayout>  </android.support.design.widget.coordinatorlayout> 

the problem when collapsed, toolbar appearing white (default gray color) can see in image.

if add background attribute toolbar in xml, toolbar appearing when not collapsed