fragment_container.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white">

    <include layout="@layout/default_toolbar" />

    <FrameLayout
        android:id="@+id/fragment_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/default_toolbar" />

</RelativeLayout>