fix: Use a pre-made preference theme

Author: feildmaster

app/build.gradle

@@ -79,6 +79,7 @@ dependencies {
     compile 'com.android.support:support-v4:26.0.1'
     compile 'com.android.support:support-vector-drawable:26.0.1'
     compile 'com.android.support:preference-v7:26.0.1'
+    compile 'com.android.support:preference-v14:26.0.1'
     compile 'com.wdullaer:materialdatetimepicker:3.2.2'
     testCompile 'junit:junit:4.12'
 }

app/src/main/res/values/styles.xml

@@ -6,7 +6,7 @@
         <item name="colorPrimary">@color/colorPrimary</item>
         <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
         <item name="colorAccent">@color/colorAccent</item>
-        <item name="preferenceTheme">@style/WhenPreferenceThemeOverlay</item>
+        <item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
     </style>
 
     <style name="AppTheme.NoActionBar" parent="AppTheme">
@@ -24,13 +24,4 @@
         <item name="android:textColor">@android:color/white</item>
     </style>
 
-    <!-- Custom Preference Theme Overlay -->
-    <style name="WhenPreferenceThemeOverlay">
-        <item name="colorPrimary">@color/colorPrimary</item>
-        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
-        <item name="colorAccent">@color/colorAccent</item>
-        <item name="preferenceFragmentCompatStyle">@style/PreferenceFragment</item>
-        <item name="preferenceStyle">@style/Preference</item>
-    </style>
-
 </resources>