FairEmail/app/src/main/res/layout/fragment_rules.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
    tools:context=".ActivityView">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/rvRule"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:scrollbarStyle="outsideOverlay"
            android:scrollbars="vertical"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <eu.faircode.email.ContentLoadingProgressBar
            android:id="@+id/pbWait"
            style="@style/Base.Widget.AppCompat.ProgressBar"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:indeterminate="true"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.Group
            android:id="@+id/grpReady"
            android:layout_width="0dp"
            android:layout_height="0dp"
            app:constraint_referenced_ids="rvRule" />
    </androidx.constraintlayout.widget.ConstraintLayout>

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_margin="@dimen/fab_padding"
        android:src="@drawable/baseline_add_24"
        android:tint="@color/colorActionForeground"
        android:tooltipText="@string/title_add"
        app:backgroundTint="?attr/colorAccent" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>