fragment_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.starkenglish.MainActivity$PlaceholderFragment">

    <TextView
        android:id="@+id/login_status"
        android:visibility="gone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:textAlignment="center"
        android:layout_marginTop="20dp"
        />

    <!-- A CardView that contains a TextView -->

    <android.support.v7.widget.CardView
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:id="@+id/card_view"
        android:layout_gravity="center"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        card_view:cardCornerRadius="0dp"
        android:layout_margin="10dp"
        android:focusable="true"
        android:elevation="3dp"
        android:paddingRight="20dp"
        android:paddingLeft="20dp"
        android:showDividers="beginning">

        <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:layout_marginTop="10dp"
            android:textAlignment="center">

            <TextView
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:text="@string/login_prompt"
                android:gravity="center"
                android:id="@+id/textView"
                android:textAlignment="center" />

            <TextView
                android:id="@+id/lesson_one"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:gravity="center"
                android:text="@string/login_prompt_help"
                android:textSize="14dp"
                android:textIsSelectable="false" />

            <com.google.android.gms.common.SignInButton
                android:id="@+id/login_with_google"
                android:text="@string/login_with_google"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:clickable="true"
                android:paddingTop="15dp"
                android:paddingBottom="5dp" />
        </LinearLayout>
    </android.support.v7.widget.CardView>

    <android.support.v7.widget.CardView
        xmlns:card_view="http://schemas.android.com/apk/res-auto"
        android:id="@+id/card_view_skip"
        android:layout_gravity="center"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        card_view:cardCornerRadius="0dp"
        android:layout_margin="10dp"
        android:focusable="true"
        android:elevation="3dp"
        android:paddingRight="20dp"
        android:paddingLeft="20dp"
        android:showDividers="beginning">
        <TextView
            android:id="@+id/textViewSkip"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="Skip this step"
            android:textSize="18dp"
            android:textIsSelectable="false"
            android:layout_margin="10dp"
            android:textColor="@android:color/holo_blue_dark" />
    </android.support.v7.widget.CardView>
</LinearLayout>