diff --git a/app/src/main/java/com/philliphsu/clock2/BaseActivity.java b/app/src/main/java/com/philliphsu/clock2/BaseActivity.java
index 45271c1..1a86ebc 100644
--- a/app/src/main/java/com/philliphsu/clock2/BaseActivity.java
+++ b/app/src/main/java/com/philliphsu/clock2/BaseActivity.java
@@ -41,12 +41,14 @@ public abstract class BaseActivity extends AppCompatActivity {
         PreferenceManager.setDefaultValues(this, R.xml.preferences, false);
         // ========================================================================================
         // TOneverDO: Set theme after setContentView()
-        // Since the default theme is light, we only need to check against the dark theme.
-        String themeDark = getString(R.string.theme_dark);
+        final String themeDark = getString(R.string.theme_dark);
+        final String themeBlack = getString(R.string.theme_black);
         String theme = PreferenceManager.getDefaultSharedPreferences(this).getString(
                 getString(R.string.key_theme), null);
         if (themeDark.equals(theme)) {
             setTheme(R.style.AppTheme_Dark);
+        } else if (themeBlack.equals(theme)) {
+            setTheme(R.style.AppTheme_Black);
         }
         // ========================================================================================
         setContentView(layoutResId());
diff --git a/app/src/main/res/values-v21/styles.xml b/app/src/main/res/values-v21/styles.xml
index 5efe5cf..16c39c0 100644
--- a/app/src/main/res/values-v21/styles.xml
+++ b/app/src/main/res/values-v21/styles.xml
@@ -27,5 +27,9 @@
         <item name="android:colorAccent">@color/colorAccentInverse</item>
         <item name="android:background">@color/alert_dialog_background_color_inverse</item>
     </style>
+    <style name="AlertDialogStyle.Black">
+        <item name="android:colorAccent">@color/colorAccentBlack</item>
+        <item name="android:background">@color/alert_dialog_background_color_black</item>
+    </style>
 
 </resources>
diff --git a/app/src/main/res/values/colors.xml b/app/src/main/res/values/colors.xml
index d874127..a6b08ab 100644
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -11,9 +11,12 @@
     <color name="colorAccentInverse">#FF5252</color>
     <color name="colorPrimaryFallbackInverse">#303030</color>
 
+    <color name="colorAccentBlack">#FF5252</color>
+
     <color name="card_background_color">#1fffffff</color> <!--12% white, not from MD spec-->
     <color name="card_background_color_inverse">#0fffffff</color> <!--6% white, not from MD spec-->
 
     <color name="alert_dialog_background_color">@color/colorPrimaryFallback</color>
     <color name="alert_dialog_background_color_inverse">@color/colorPrimaryFallbackInverse</color>
+    <color name="alert_dialog_background_color_black">#111111</color>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/prefs_general.xml b/app/src/main/res/values/prefs_general.xml
index dadb93f..553d6ed 100644
--- a/app/src/main/res/values/prefs_general.xml
+++ b/app/src/main/res/values/prefs_general.xml
@@ -8,9 +8,11 @@
 
     <string name="theme_light">Light</string>
     <string name="theme_dark">Dark</string>
+    <string name="theme_black">Black</string>
     <string-array name="array_theme">
         <item>@string/theme_light</item>
         <item>@string/theme_dark</item>
+        <item>@string/theme_black</item>
     </string-array>
 
     <string name="key_last_tab">last_tab</string>
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index 86e360e..fa6f7e6 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -34,12 +34,24 @@
         <item name="android:windowBackground">@color/colorPrimaryInverse</item>
     </style>
 
+    <style name="BaseAppTheme.Black">
+        <item name="colorPrimary">@android:color/black</item>
+        <item name="colorPrimaryDark">@android:color/black</item>
+        <item name="colorAccent">@color/colorAccentBlack</item>
+        <item name="cardBackgroundColor">@color/card_background_color_inverse</item>
+        <item name="alertDialogTheme">@style/AppCompatAlertDialogStyle.Black</item>
+        <item name="android:windowBackground">@android:color/black</item>
+    </style>
+
     <style name="AppTheme" parent="BaseAppTheme.Light">
     </style>
 
     <style name="AppTheme.Dark" parent="BaseAppTheme.Dark">
     </style>
 
+    <style name="AppTheme.Black" parent="BaseAppTheme.Black">
+    </style>
+
     <style name="NumberButton">
         <item name="android:layout_width">0dp</item>
         <item name="android:layout_height">match_parent</item>
@@ -138,11 +150,14 @@
         <item name="colorAccent">@color/colorAccent</item>
         <item name="android:background">@color/alert_dialog_background_color</item>
     </style>
-
     <style name="AppCompatAlertDialogStyle.Dark">
         <item name="colorAccent">@color/colorAccentInverse</item>
         <item name="android:background">@color/alert_dialog_background_color_inverse</item>
     </style>
+    <style name="AppCompatAlertDialogStyle.Black">
+        <item name="colorAccent">@color/colorAccentBlack</item>
+        <item name="android:background">@color/alert_dialog_background_color_black</item>
+    </style>
 
     <style name="BottomSheetDialogTheme" parent="Theme.Design.Light.BottomSheetDialog">
         <item name="bottomSheetStyle">@style/ModalStyle</item>