Back button now functional

app/src/main/AndroidManifest.xml

@@ -10,17 +10,19 @@
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".ui.activities.MainActivity">
+        <activity android:name=".ui.activities.MainActivity"
+                  android:launchMode="singleTop">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
 
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
-        <activity android:name=".ui.activities.DetailActivity">
-            <intent-filter>
-                <action android:name="android.intent.action.DETAIL"/>
-            </intent-filter>
+        <activity android:name=".ui.activities.DetailActivity"
+                  android:parentActivityName=".ui.activities.MainActivity">
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value=".ui.activities.MainActivity"/>
         </activity>
     </application>