title: Why is the background of my buttons not changing
body: <p>I'm trying to create a global style where my buttons have a dark grey background with white text. The text color is fine. I'm able to change it but for some reason the background color of the buttons wont change. What am I doing wrong. </p>
  
  <p>Here is my colors xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;resources&gt;
      &lt;color name="colorPrimary"&gt;#bf360c&lt;/color&gt;
      &lt;color name="colorPrimaryLight"&gt;#f9683a&lt;/color&gt;
      &lt;color name="colorPrimaryDark"&gt;#870000&lt;/color&gt;
      &lt;color name="colorPrimaryText"&gt;#000000&lt;/color&gt;
      &lt;color name="colorAccent"&gt;#a4a4a4&lt;/color&gt;
      &lt;color name="colorWindowBackground"&gt;#fafafa&lt;/color&gt;
  
      &lt;color name="RED"&gt;#ff0000&lt;/color&gt;
      &lt;color name="BLUE"&gt;#000fff&lt;/color&gt;
      &lt;color name="GREEN"&gt;#00FF00&lt;/color&gt;
      &lt;color name="YELLOW"&gt;#FFEB3B&lt;/color&gt;
      &lt;color name="DARK_GREY"&gt;#494949&lt;/color&gt;
  &lt;/resources&gt;
  </code></pre>
  
  <p>Here is my styles xml:</p>
  
  <pre><code>&lt;resources&gt;
  
      &lt;!-- Base application theme. --&gt;
      &lt;style name="AppTheme" parent="@style/Theme.AppCompat"&gt;
          &lt;!-- Customize your theme here. --&gt;
          &lt;item name="colorPrimary"&gt;@color/colorPrimary&lt;/item&gt;
          &lt;item name="colorPrimaryDark"&gt;@color/colorPrimaryDark&lt;/item&gt;
          &lt;item name="colorAccent"&gt;@color/colorAccent&lt;/item&gt;
          &lt;item name="android:textColor"&gt;@color/colorPrimaryText&lt;/item&gt;
          &lt;item name="android:textColorSecondary"&gt;@color/colorAccent&lt;/item&gt;
          &lt;item name="android:windowBackground"&gt;@color/colorWindowBackground&lt;/item&gt;
          &lt;item name="android:buttonStyle"&gt;@style/buttonColor&lt;/item&gt;
  
      &lt;/style&gt;
  
      &lt;style name="buttonColor" parent="android:style/Widget.Button"&gt;
          &lt;item name="android:textColor"&gt;@color/colorWindowBackground&lt;/item&gt;
          &lt;item name="android:colorBackground"&gt;@color/DARK_GREY&lt;/item&gt;
      &lt;/style&gt;
  
  &lt;/resources&gt;
  </code></pre>
  
  <p>And why did my exit button shrink all of a sudden?
  <a href="https://i.stack.imgur.com/qHAeR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qHAeR.png" alt="enter image description here"></a></p>
  
  <p>Now I have this but the exit button shrank??????</p>
  
  <p><a href="https://i.stack.imgur.com/LCgVD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LCgVD.png" alt="enter image description here"></a></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.constraint.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"
      android:layout_margin="16dp"
      tools:context="com.checkinsystems.ez_score.MainActivity"&gt;
  
      &lt;Button
          android:id="@+id/match_button"
          android:layout_width="0dp"
          android:layout_height="65dp"
          android:onClick="goToMatchScreen"
          android:text="@string/match_button"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toTopOf="parent"/&gt;
  
      &lt;Button
          android:id="@+id/competitors_button"
          android:layout_width="0dp"
          android:layout_height="65dp"
          android:layout_marginTop="15dp"
          android:onClick="goToCompetitorsScreen"
          android:text="@string/competitors_button"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toBottomOf="@+id/match_button"/&gt;
  
      &lt;Button
          android:id="@+id/scores_button"
          android:layout_width="0dp"
          android:layout_height="65dp"
          android:layout_marginTop="15dp"
          android:onClick="goToScoresScreen"
          android:text="@string/scores_button"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toBottomOf="@+id/competitors_button"/&gt;
  
      &lt;Button
          android:id="@+id/reports_button"
          android:layout_width="0dp"
          android:layout_height="65dp"
          android:layout_marginTop="15dp"
          android:onClick="goToReportsActivity"
          android:text="@string/reports_button"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toBottomOf="@+id/scores_button"/&gt;
  
      &lt;Button
          android:id="@+id/exit_button"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/exit_button"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintLeft_toLeftOf="parent"/&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>