zumo_2.0_android/app/src/main/res/layout/fragment_login.xml

<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@color/colorAccent"
  android:orientation="horizontal"
  tools:fragmentActivity=".LoginFragment">

  <!--<Button
    android:id="@+id/button_back"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Back"/>-->

</LinearLayout>