MystereARecouvrance/app/src/main/res/layout/activity_settings.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFFFF"
    android:weightSum="1">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="493dp"
            android:layout_gravity="center_horizontal"
            android:id="@+id/root_layout"
            android:layout_above="@+id/button3"
            android:layout_alignParentTop="true"
            android:measureWithLargestChild="false" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="OK"
            android:id="@+id/button3"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:onClick="onClick" />
    </RelativeLayout>
</LinearLayout>