diff --git a/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt b/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt
index b61b2f7c..84e607dd 100644
--- a/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt
+++ b/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt
@@ -26,6 +26,7 @@ import android.view.Menu
 import android.view.MenuItem
 import android.view.View
 import androidx.appcompat.app.AppCompatActivity
+import androidx.appcompat.app.AppCompatDelegate
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
 import androidx.core.view.GravityCompat
 import androidx.drawerlayout.widget.DrawerLayout
@@ -61,7 +62,9 @@ class MainActivity :
 
         val settings = mainContext.settings
         settings.initializeDefaultValues()
-        setTheme(settings.themeStyle().themeNoActionBar)
+        val themeStyle = settings.themeStyle()
+        AppCompatDelegate.setDefaultNightMode(themeStyle.nightMode)
+        setTheme(themeStyle.themeNoActionBar)
 
         mainReload = MainReload(settings)
 
diff --git a/app/src/main/kotlin/com/vrem/wifianalyzer/settings/Settings.kt b/app/src/main/kotlin/com/vrem/wifianalyzer/settings/Settings.kt
index acf95922..d2ff2024 100644
--- a/app/src/main/kotlin/com/vrem/wifianalyzer/settings/Settings.kt
+++ b/app/src/main/kotlin/com/vrem/wifianalyzer/settings/Settings.kt
@@ -106,7 +106,7 @@ class Settings(
     fun keepScreenOn(): Boolean =
         repository.boolean(R.string.keep_screen_on_key, repository.resourceBoolean(R.bool.keep_screen_on_default))
 
-    fun themeStyle(): ThemeStyle = settingsFind(ThemeStyle.entries, R.string.theme_key, ThemeStyle.DARK)
+    fun themeStyle(): ThemeStyle = settingsFind(ThemeStyle.entries, R.string.theme_key, ThemeStyle.SYSTEM)
 
     fun selectedMenu(): NavigationMenu =
         settingsFind(NavigationMenu.entries, R.string.selected_menu_key, NavigationMenu.ACCESS_POINTS)
diff --git a/app/src/main/kotlin/com/vrem/wifianalyzer/settings/ThemeStyle.kt b/app/src/main/kotlin/com/vrem/wifianalyzer/settings/ThemeStyle.kt
index 6f638576..f457f599 100644
--- a/app/src/main/kotlin/com/vrem/wifianalyzer/settings/ThemeStyle.kt
+++ b/app/src/main/kotlin/com/vrem/wifianalyzer/settings/ThemeStyle.kt
@@ -20,15 +20,17 @@ package com.vrem.wifianalyzer.settings
 import android.graphics.Color
 import androidx.annotation.ColorInt
 import androidx.annotation.StyleRes
+import androidx.appcompat.app.AppCompatDelegate
 import com.vrem.wifianalyzer.R
 
 enum class ThemeStyle(
     @param:StyleRes val theme: Int,
     @param:StyleRes val themeNoActionBar: Int,
     @param:ColorInt val colorGraphText: Int,
+    val nightMode: Int,
 ) {
-    DARK(R.style.ThemeDark, R.style.ThemeDarkNoActionBar, Color.WHITE),
-    LIGHT(R.style.ThemeLight, R.style.ThemeLightNoActionBar, Color.BLACK),
-    SYSTEM(R.style.ThemeSystem, R.style.ThemeSystemNoActionBar, Color.GRAY),
-    BLACK(R.style.ThemeBlack, R.style.ThemeBlackNoActionBar, Color.WHITE),
+    DARK(R.style.ThemeSystem, R.style.ThemeSystemNoActionBar, Color.WHITE, AppCompatDelegate.MODE_NIGHT_YES),
+    LIGHT(R.style.ThemeSystem, R.style.ThemeSystemNoActionBar, Color.BLACK, AppCompatDelegate.MODE_NIGHT_NO),
+    SYSTEM(R.style.ThemeSystem, R.style.ThemeSystemNoActionBar, Color.GRAY, AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM),
+    BLACK(R.style.ThemeBlack, R.style.ThemeBlackNoActionBar, Color.WHITE, AppCompatDelegate.MODE_NIGHT_YES),
 }
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index 60e7451e..50a3c57b 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -18,26 +18,6 @@
 
 <resources>
 
-    <!-- Dark theme -->
-    <style name="ThemeDark" parent="Theme.AppCompat">
-        <item name="android:windowAnimationStyle">@style/WindowAnimationTransition</item>
-        <item name="android:actionMenuTextColor">@color/selected</item>
-    </style>
-    <style name="ThemeDarkNoActionBar" parent="ThemeDark">
-        <item name="windowActionBar">false</item>
-        <item name="windowNoTitle">true</item>
-    </style>
-
-    <!-- Light theme -->
-    <style name="ThemeLight" parent="Theme.AppCompat.Light.DarkActionBar">
-        <item name="android:windowAnimationStyle">@style/WindowAnimationTransition</item>
-        <item name="android:actionMenuTextColor">@color/selected</item>
-    </style>
-    <style name="ThemeLightNoActionBar" parent="ThemeLight">
-        <item name="windowActionBar">false</item>
-        <item name="windowNoTitle">true</item>
-    </style>
-
     <!-- Black theme -->
     <style name="ThemeBlack" parent="Theme.AppCompat">
         <item name="android:windowAnimationStyle">@style/WindowAnimationTransition</item>
diff --git a/app/src/test/kotlin/com/vrem/wifianalyzer/settings/SettingsTest.kt b/app/src/test/kotlin/com/vrem/wifianalyzer/settings/SettingsTest.kt
index 90c7579d..57cbdbb3 100644
--- a/app/src/test/kotlin/com/vrem/wifianalyzer/settings/SettingsTest.kt
+++ b/app/src/test/kotlin/com/vrem/wifianalyzer/settings/SettingsTest.kt
@@ -174,14 +174,14 @@ class SettingsTest {
             // setup
             doReturn(it.ordinal)
                 .whenever(repository)
-                .stringAsInteger(R.string.theme_key, ThemeStyle.DARK.ordinal)
+                .stringAsInteger(R.string.theme_key, ThemeStyle.SYSTEM.ordinal)
             // execute
             val actual = fixture.themeStyle()
             // validate
             assertThat(actual).describedAs("Theme: $it").isEqualTo(it)
         }
         verify(repository, times(ThemeStyle.entries.size))
-            .stringAsInteger(R.string.theme_key, ThemeStyle.DARK.ordinal)
+            .stringAsInteger(R.string.theme_key, ThemeStyle.SYSTEM.ordinal)
     }
 
     @Test
@@ -189,12 +189,12 @@ class SettingsTest {
         // setup
         doReturn(ThemeStyle.entries.size)
             .whenever(repository)
-            .stringAsInteger(R.string.theme_key, ThemeStyle.DARK.ordinal)
+            .stringAsInteger(R.string.theme_key, ThemeStyle.SYSTEM.ordinal)
         // execute
         val actual = fixture.themeStyle()
         // validate
-        assertThat(actual).isEqualTo(ThemeStyle.DARK)
-        verify(repository).stringAsInteger(R.string.theme_key, ThemeStyle.DARK.ordinal)
+        assertThat(actual).isEqualTo(ThemeStyle.SYSTEM)
+        verify(repository).stringAsInteger(R.string.theme_key, ThemeStyle.SYSTEM.ordinal)
     }
 
     @Test
diff --git a/app/src/test/kotlin/com/vrem/wifianalyzer/settings/ThemeStyleTest.kt b/app/src/test/kotlin/com/vrem/wifianalyzer/settings/ThemeStyleTest.kt
index 39487e3a..71e7225d 100644
--- a/app/src/test/kotlin/com/vrem/wifianalyzer/settings/ThemeStyleTest.kt
+++ b/app/src/test/kotlin/com/vrem/wifianalyzer/settings/ThemeStyleTest.kt
@@ -18,6 +18,7 @@
 package com.vrem.wifianalyzer.settings
 
 import android.graphics.Color
+import androidx.appcompat.app.AppCompatDelegate
 import com.vrem.wifianalyzer.R
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.Test
@@ -32,16 +33,16 @@ class ThemeStyleTest {
 
     @Test
     fun theme() {
-        assertThat(ThemeStyle.LIGHT.theme).isEqualTo(R.style.ThemeLight)
-        assertThat(ThemeStyle.DARK.theme).isEqualTo(R.style.ThemeDark)
+        assertThat(ThemeStyle.LIGHT.theme).isEqualTo(R.style.ThemeSystem)
+        assertThat(ThemeStyle.DARK.theme).isEqualTo(R.style.ThemeSystem)
         assertThat(ThemeStyle.SYSTEM.theme).isEqualTo(R.style.ThemeSystem)
         assertThat(ThemeStyle.BLACK.theme).isEqualTo(R.style.ThemeBlack)
     }
 
     @Test
     fun themeNoActionBar() {
-        assertThat(ThemeStyle.DARK.themeNoActionBar).isEqualTo(R.style.ThemeDarkNoActionBar)
-        assertThat(ThemeStyle.LIGHT.themeNoActionBar).isEqualTo(R.style.ThemeLightNoActionBar)
+        assertThat(ThemeStyle.DARK.themeNoActionBar).isEqualTo(R.style.ThemeSystemNoActionBar)
+        assertThat(ThemeStyle.LIGHT.themeNoActionBar).isEqualTo(R.style.ThemeSystemNoActionBar)
         assertThat(ThemeStyle.SYSTEM.themeNoActionBar).isEqualTo(R.style.ThemeSystemNoActionBar)
         assertThat(ThemeStyle.BLACK.themeNoActionBar).isEqualTo(R.style.ThemeBlackNoActionBar)
     }
@@ -54,6 +55,14 @@ class ThemeStyleTest {
         assertThat(ThemeStyle.BLACK.colorGraphText).isEqualTo(Color.WHITE)
     }
 
+    @Test
+    fun nightMode() {
+        assertThat(ThemeStyle.DARK.nightMode).isEqualTo(AppCompatDelegate.MODE_NIGHT_YES)
+        assertThat(ThemeStyle.LIGHT.nightMode).isEqualTo(AppCompatDelegate.MODE_NIGHT_NO)
+        assertThat(ThemeStyle.SYSTEM.nightMode).isEqualTo(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
+        assertThat(ThemeStyle.BLACK.nightMode).isEqualTo(AppCompatDelegate.MODE_NIGHT_YES)
+    }
+
     @Test
     fun themeStyleOrdinal() {
         assertThat(ThemeStyle.DARK.ordinal).isEqualTo(0)