How do I decrease the space between cards in a CardView within a RecyclerView?

Question

I'm working on a layout for the main screen of my app. I'm using a RecyclerView with a grid layout and a CardView within that. I'm trying to decrease the space between each card. A screenshot is below (with layout outlines turned on) as well as my layout files. How can I get each card to be a bit closer to each other vertically as well as horizontally? I've been playing around with margins a lot and I just can't seem to find the right margin or padding value to do this.

thumbnail_view.xml:

<?xml version="1.0" encoding="utf-8"?>

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:id="@+id/card_view"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    card_view:cardCornerRadius="5dp"
    card_view:cardMaxElevation="15dp"
    card_view:cardElevation="10dp"
    card_view:contentPadding="5dp"
    android:padding="1dp"
    card_view:cardBackgroundColor="@color/colorPrimary"
    card_view:cardUseCompatPadding="true"
    card_view:cardPreventCornerOverlap="false"
    >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:id="@+id/card_list">
        <ImageView
            android:id="@+id/thumbnail"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:gravity="center"
            android:contentDescription="@string/video_thumbnail_description"
            android:layout_weight="1"
            />

        <TextView
            android:id="@+id/video_title_view"
            android:layout_height="match_parent"
            android:layout_width="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:layout_weight="2"
            />
    </LinearLayout>
</android.support.v7.widget.CardView>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.app.int_a.giantbombforandroid.main.mainscreen.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_list"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</RelativeLayout>

Answer 1

Edit these attributes

card_view:cardMaxElevation="1dp"
card_view:cardElevation="1dp"

so full code will be

<?xml version="1.0" encoding="utf-8"?>

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:id="@+id/card_view"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    card_view:cardCornerRadius="5dp"
    card_view:cardMaxElevation="1dp"
    card_view:cardElevation="1dp"
      card_view:cardBackgroundColor="@color/colorPrimary"
    card_view:cardUseCompatPadding="true"
    card_view:cardPreventCornerOverlap="false"
    >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:id="@+id/card_list">
        <ImageView
            android:id="@+id/thumbnail"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="center"
            android:gravity="center"
            android:src="@drawable/bag"
            android:contentDescription="string/video_thumbnail_description"
            android:layout_weight="1"
            />

        <TextView
            android:id="@+id/video_title_view"
            android:layout_height="match_parent"
            android:layout_width="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:text="lovelksdjslkdjlsdj"
            android:layout_weight="3"
            />
    </LinearLayout>
</android.support.v7.widget.CardView>