diff --git a/app/src/androidTest/kotlin/com/vrem/wifianalyzer/MainInstrumentedTest.kt b/app/src/androidTest/kotlin/com/vrem/wifianalyzer/MainInstrumentedTest.kt
index 7fc055e3..2802cdd7 100644
--- a/app/src/androidTest/kotlin/com/vrem/wifianalyzer/MainInstrumentedTest.kt
+++ b/app/src/androidTest/kotlin/com/vrem/wifianalyzer/MainInstrumentedTest.kt
@@ -115,4 +115,9 @@ class MainInstrumentedTest {
     fun settings() {
         SettingsInstrumentedTest().run()
     }
+
+    @Test
+    fun theme() {
+        ThemeInstrumentedTest().run()
+    }
 }
diff --git a/app/src/androidTest/kotlin/com/vrem/wifianalyzer/ThemeInstrumentedTest.kt b/app/src/androidTest/kotlin/com/vrem/wifianalyzer/ThemeInstrumentedTest.kt
new file mode 100644
index 00000000..6f93d3fe
--- /dev/null
+++ b/app/src/androidTest/kotlin/com/vrem/wifianalyzer/ThemeInstrumentedTest.kt
@@ -0,0 +1,66 @@
+/*
+ * WiFiAnalyzer
+ * Copyright (C) 2026 VREM Software Development <VREMSoftwareDevelopment@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+package com.vrem.wifianalyzer
+
+import androidx.appcompat.app.AppCompatDelegate
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.Espresso.pressBack
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.withText
+import org.junit.Assert.assertEquals
+
+internal class ThemeInstrumentedTest : Runnable {
+    override fun run() {
+        verifyThemeSettings()
+
+        listOf(
+            "Dark" to AppCompatDelegate.MODE_NIGHT_YES,
+            "Light" to AppCompatDelegate.MODE_NIGHT_NO,
+            "System" to AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM,
+            "Black" to AppCompatDelegate.MODE_NIGHT_YES,
+        ).forEach { (themeName, expectedNightMode) ->
+            changeThemeAndVerify(themeName, expectedNightMode)
+        }
+    }
+
+    private fun verifyThemeSettings() {
+        selectMenuItem(R.id.nav_drawer_settings, "Settings")
+        scrollToAndVerify("Theme")
+        pressBack()
+    }
+
+    private fun changeThemeAndVerify(
+        themeName: String,
+        expectedNightMode: Int,
+    ) {
+        selectMenuItem(R.id.nav_drawer_settings, "Settings")
+        scrollToAndVerify("Theme")
+        onView(withText("Theme")).perform(click())
+        pauseShort()
+        onView(withText(themeName)).check(matches(isDisplayed()))
+        onView(withText(themeName)).perform(click())
+        pauseShort()
+        assertEquals(
+            "Theme $themeName should set night mode to $expectedNightMode",
+            expectedNightMode,
+            AppCompatDelegate.getDefaultNightMode(),
+        )
+    }
+}
diff --git a/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt b/app/src/main/kotlin/com/vrem/wifianalyzer/MainActivity.kt
index b61b2f7c..52df659f 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 +62,11 @@ class MainActivity :
 
         val settings = mainContext.settings
         settings.initializeDefaultValues()
-        setTheme(settings.themeStyle().themeNoActionBar)
+
+        settings.themeStyle().apply {
+            AppCompatDelegate.setDefaultNightMode(nightMode)
+            setTheme(themeNoActionBar)
+        }
 
         mainReload = MainReload(settings)
 
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/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)