android cardview showing border around card

Android cardview is showing unnecessary border around the card. I have tried different things but I am not able to remove it. It happens when I give the card a custom background color. When I remove the cardBackgroundColor, and when default is used. Then unnecessary border is not visible.

I have to use shadow and tranparent color code.

Here is my layout CardView

         <RelativeLayout
            android:id="@+id/rlUserNamePassword"
            android:layout_width="match_parent"
            android:background="@android:color/transparent"
            android:layout_height="wrap_content">

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/margin"
                android:background="@android:color/transparent"
                app:cardBackgroundColor="@color/form_card_bg_color"
                app:cardElevation="@dimen/margin"
                app:contentPadding="@dimen/margin_large"
                app:cardPreventCornerOverlap="false"
                app:cardUseCompatPadding="true" >

                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:orientation="vertical">

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:gravity="center_vertical"
                        android:orientation="horizontal">

                        <ImageView
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:src="@drawable/user" />

                        <android.support.design.widget.TextInputLayout
                            android:id="@+id/tilName"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content">

                            <com.yaashvi.placeandpeople.customviews.CustomEditText
                                android:id="@+id/etEmail"
                                android:layout_width="match_parent"
                                android:layout_height="wrap_content"
                                android:hint="@string/username"
                                android:singleLine="true"
                                android:maxLines="1"/>

                        </android.support.design.widget.TextInputLayout>

                    </LinearLayout>

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_marginBottom="@dimen/margin_large"
                        android:gravity="center_vertical"
                        android:orientation="horizontal">

                        <ImageView
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:src="@drawable/password" />

                        <android.support.design.widget.TextInputLayout
                            android:id="@+id/tilPassword"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content">

                            <com.yaashvi.placeandpeople.customviews.CustomEditText
                                android:id="@+id/etPassword"
                                android:layout_width="match_parent"
                                android:layout_height="wrap_content"
                                android:hint="@string/password"
                                android:singleLine="true"
                                android:maxLines="1"
                                android:inputType="textPassword"/>
                        </android.support.design.widget.TextInputLayout>

                    </LinearLayout>
                </LinearLayout>

            </android.support.v7.widget.CardView >

            <LinearLayout
                android:id="@+id/llGo"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:layout_alignParentRight="true"
                android:orientation="vertical"
                android:elevation="@dimen/margin_large"
                >

                <include layout="@layout/go_button" />

            </LinearLayout>

        </RelativeLayout>

And the view created is this

See the extra border on left, right and top of cardview and inside the card shadow.