FA GOOGLE LoginWithPhoneAuth-activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">
        
        <!--  TextView asking for phone number -->
        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_marginTop="168dp"
            android:text="May I ask your phone number?"
            android:textAppearance="@style/Base.TextAppearance.AppCompat.Headline"
            android:textColor="@color/colorPrimary"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.367"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <!--  EditText where user can write phone number-->
        <EditText
            android:id="@+id/editTextMobile"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_margin="32dp"
            android:layout_marginTop="284dp"
            android:digits="0123456789"
            android:hint="enter your mobile number"
            android:inputType="phone"
            android:maxLength="12"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.25"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/textView" />

        <!--  Button to continue the process -->
        <Button
            android:id="@+id/buttonContinue"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_marginTop="324dp"
            android:background="@color/colorPrimaryDark"
            android:text="Continue"
            android:textAllCaps="false"
            android:textColor="#cdd8f1"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </androidx.constraintlayout.widget.ConstraintLayout>