diff --git a/app/build.gradle b/app/build.gradle
index c29a25c9..7f63220f 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -19,11 +19,10 @@ android {
     defaultConfig {
         applicationId "io.github.wulkanowy"
         testApplicationId "io.github.tests.wulkanowy"
-        minSdkVersion 17
+        minSdkVersion 21
         targetSdkVersion 30
         versionCode 90
         versionName "1.1.4"
-        multiDexEnabled true
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
 
@@ -78,7 +77,6 @@ android {
     productFlavors {
         hms {
             dimension "platform"
-            minSdkVersion 19
             manifestPlaceholders = [
                     install_channel: "AppGallery"
             ]
@@ -175,7 +173,6 @@ dependencies {
     implementation "androidx.appcompat:appcompat-resources:1.2.0"
     implementation "androidx.fragment:fragment-ktx:1.3.2"
     implementation "androidx.annotation:annotation:1.2.0"
-    implementation "androidx.multidex:multidex:2.0.1"
 
     implementation "androidx.preference:preference-ktx:1.1.1"
     implementation "androidx.recyclerview:recyclerview:1.1.0"
diff --git a/app/jacoco.gradle b/app/jacoco.gradle
index 94469fbc..1fb1ebd7 100644
--- a/app/jacoco.gradle
+++ b/app/jacoco.gradle
@@ -1,8 +1,8 @@
 apply plugin: "jacoco"
 
 jacoco {
-    toolVersion "0.8.5"
-    reportsDir = file("$buildDir/reports")
+    toolVersion "0.8.6"
+    reportsDirectory = file("$buildDir/reports")
 }
 
 tasks.withType(Test) {
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 7b714fb2..3b6b9e66 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -6,6 +6,7 @@
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
     <uses-permission android:name="android.permission.VIBRATE" />
 
diff --git a/app/src/main/java/io/github/wulkanowy/WulkanowyApp.kt b/app/src/main/java/io/github/wulkanowy/WulkanowyApp.kt
index d01a953d..09083467 100644
--- a/app/src/main/java/io/github/wulkanowy/WulkanowyApp.kt
+++ b/app/src/main/java/io/github/wulkanowy/WulkanowyApp.kt
@@ -2,14 +2,12 @@ package io.github.wulkanowy
 
 import android.annotation.SuppressLint
 import android.app.Application
-import android.content.Context
 import android.util.Log.DEBUG
 import android.util.Log.INFO
 import android.util.Log.VERBOSE
 import android.webkit.WebView
 import androidx.fragment.app.FragmentManager
 import androidx.hilt.work.HiltWorkerFactory
-import androidx.multidex.MultiDex
 import androidx.work.Configuration
 import com.yariksoffice.lingver.Lingver
 import dagger.hilt.android.HiltAndroidApp
@@ -43,11 +41,6 @@ class WulkanowyApp : Application(), Configuration.Provider {
     @Inject
     lateinit var analyticsHelper: AnalyticsHelper
 
-    override fun attachBaseContext(base: Context?) {
-        super.attachBaseContext(base)
-        MultiDex.install(this)
-    }
-
     @SuppressLint("UnsafeOptInUsageWarning")
     override fun onCreate() {
         super.onCreate()
diff --git a/app/src/main/java/io/github/wulkanowy/data/repositories/AppCreatorRepository.kt b/app/src/main/java/io/github/wulkanowy/data/repositories/AppCreatorRepository.kt
index aea8632a..71b7ea94 100644
--- a/app/src/main/java/io/github/wulkanowy/data/repositories/AppCreatorRepository.kt
+++ b/app/src/main/java/io/github/wulkanowy/data/repositories/AppCreatorRepository.kt
@@ -15,6 +15,7 @@ class AppCreatorRepository @Inject constructor(
     private val dispatchers: DispatchersProvider
 ) {
 
+    @Suppress("BlockingMethodInNonBlockingContext")
     suspend fun getAppCreators() = withContext(dispatchers.backgroundThread) {
         val moshi = Moshi.Builder().build()
         val type = Types.newParameterizedType(List::class.java, Contributor::class.java)
diff --git a/app/src/main/java/io/github/wulkanowy/data/repositories/PreferencesRepository.kt b/app/src/main/java/io/github/wulkanowy/data/repositories/PreferencesRepository.kt
index 375dd62e..426e08ff 100644
--- a/app/src/main/java/io/github/wulkanowy/data/repositories/PreferencesRepository.kt
+++ b/app/src/main/java/io/github/wulkanowy/data/repositories/PreferencesRepository.kt
@@ -2,7 +2,6 @@ package io.github.wulkanowy.data.repositories
 
 import android.content.Context
 import android.content.SharedPreferences
-import androidx.core.content.edit
 import dagger.hilt.android.qualifiers.ApplicationContext
 import io.github.wulkanowy.R
 import io.github.wulkanowy.ui.modules.grade.GradeAverageMode
@@ -151,10 +150,6 @@ class PreferencesRepository @Inject constructor(
             R.string.pref_key_optional_arithmetic_average,
             R.bool.pref_default_optional_arithmetic_average
         )
-  
-    var isKitkatDialogDisabled: Boolean
-        get() = sharedPref.getBoolean("kitkat_dialog_disabled", false)
-        set(value) = sharedPref.edit { putBoolean("kitkat_dialog_disabled", value) }
 
     private fun getString(id: Int, default: Int) = getString(context.getString(id), default)
 
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/about/logviewer/LogViewerFragment.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/about/logviewer/LogViewerFragment.kt
index cf40975e..09572c97 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/about/logviewer/LogViewerFragment.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/about/logviewer/LogViewerFragment.kt
@@ -4,9 +4,6 @@ import android.content.Intent
 import android.content.Intent.EXTRA_EMAIL
 import android.content.Intent.EXTRA_STREAM
 import android.content.Intent.FLAG_GRANT_READ_URI_PERMISSION
-import android.net.Uri
-import android.os.Build.VERSION.SDK_INT
-import android.os.Build.VERSION_CODES.LOLLIPOP
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuInflater
@@ -81,8 +78,7 @@ class LogViewerFragment : BaseFragment<FragmentLogviewerBinding>(R.layout.fragme
             putExtra(EXTRA_EMAIL, arrayOf("wulkanowyinc@gmail.com"))
             addFlags(FLAG_GRANT_READ_URI_PERMISSION)
             putParcelableArrayListExtra(EXTRA_STREAM, ArrayList(files.map {
-                if (SDK_INT < LOLLIPOP) Uri.fromFile(it)
-                else FileProvider.getUriForFile(requireContext(), "$APPLICATION_ID.fileprovider", it)
+                FileProvider.getUriForFile(requireContext(), "$APPLICATION_ID.fileprovider", it)
             }))
         }
 
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/account/accountedit/AccountEditPresenter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/account/accountedit/AccountEditPresenter.kt
index 62dd70ab..67ecdb5f 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/account/accountedit/AccountEditPresenter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/account/accountedit/AccountEditPresenter.kt
@@ -14,7 +14,7 @@ import timber.log.Timber
 import javax.inject.Inject
 
 class AccountEditPresenter @Inject constructor(
-    private val appInfo: AppInfo,
+    appInfo: AppInfo,
     errorHandler: ErrorHandler,
     studentRepository: StudentRepository
 ) : BasePresenter<AccountEditView>(errorHandler, studentRepository) {
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/grade/summary/GradeSummaryAdapter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/grade/summary/GradeSummaryAdapter.kt
index edc2a9e1..4de6044b 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/grade/summary/GradeSummaryAdapter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/grade/summary/GradeSummaryAdapter.kt
@@ -5,15 +5,11 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.recyclerview.widget.RecyclerView
-import io.github.wulkanowy.data.db.entities.Grade
 import io.github.wulkanowy.data.db.entities.GradeSummary
-import io.github.wulkanowy.data.db.entities.Student
 import io.github.wulkanowy.data.repositories.PreferencesRepository
 import io.github.wulkanowy.databinding.ItemGradeSummaryBinding
 import io.github.wulkanowy.databinding.ScrollableHeaderGradeSummaryBinding
-import io.github.wulkanowy.sdk.Sdk
 import io.github.wulkanowy.utils.calcAverage
-import io.github.wulkanowy.utils.changeModifier
 import java.util.Locale
 import javax.inject.Inject
 
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryAdapter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryAdapter.kt
index 7c09c96f..2a80de8c 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryAdapter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryAdapter.kt
@@ -8,7 +8,6 @@ import io.github.wulkanowy.data.db.entities.LuckyNumber
 import io.github.wulkanowy.databinding.ItemLuckyNumberHistoryBinding
 import io.github.wulkanowy.utils.toFormattedString
 import io.github.wulkanowy.utils.weekDayName
-import java.util.Locale
 import javax.inject.Inject
 
 class LuckyNumberHistoryAdapter @Inject constructor() :
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryFragment.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryFragment.kt
index 6e991ba1..f155fa47 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryFragment.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/luckynumber/history/LuckyNumberHistoryFragment.kt
@@ -15,7 +15,6 @@ import io.github.wulkanowy.ui.modules.main.MainView
 import io.github.wulkanowy.ui.widgets.DividerItemDecoration
 import io.github.wulkanowy.utils.SchooldaysRangeLimiter
 import io.github.wulkanowy.utils.dpToPx
-import io.github.wulkanowy.utils.getThemeAttrColor
 import java.time.LocalDate
 import javax.inject.Inject
 
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainActivity.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainActivity.kt
index 741cfb18..22e39236 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainActivity.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainActivity.kt
@@ -9,8 +9,6 @@ import android.content.pm.ShortcutInfo
 import android.content.pm.ShortcutManager
 import android.graphics.drawable.Icon
 import android.os.Build
-import android.os.Build.VERSION.SDK_INT
-import android.os.Build.VERSION_CODES.LOLLIPOP
 import android.os.Build.VERSION_CODES.P
 import android.os.Bundle
 import android.view.Menu
@@ -211,7 +209,7 @@ class MainActivity : BaseActivity<MainPresenter, ActivityMainBinding>(), MainVie
     @SuppressLint("NewApi")
     override fun initView() {
         with(binding.mainToolbar) {
-            if (SDK_INT >= LOLLIPOP) stateListAnimator = null
+            stateListAnimator = null
             setBackgroundColor(
                 overlayProvider.compositeOverlayWithThemeSurfaceColorIfNeeded(dpToPx(4f))
             )
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainPresenter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainPresenter.kt
index ffcfcb61..c0eb2b11 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainPresenter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/main/MainPresenter.kt
@@ -24,7 +24,7 @@ class MainPresenter @Inject constructor(
     private val analytics: AnalyticsHelper,
 ) : BasePresenter<MainView>(errorHandler, studentRepository) {
 
-    var studentsWitSemesters: List<StudentWithSemesters>? = null
+    private var studentsWitSemesters: List<StudentWithSemesters>? = null
 
     fun onAttachView(view: MainView, initMenu: MainView.Section?) {
         super.onAttachView(view)
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/more/MoreFragment.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/more/MoreFragment.kt
index c4a14a52..d235d68b 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/more/MoreFragment.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/more/MoreFragment.kt
@@ -8,7 +8,6 @@ import dagger.hilt.android.AndroidEntryPoint
 import io.github.wulkanowy.R
 import io.github.wulkanowy.databinding.FragmentMoreBinding
 import io.github.wulkanowy.ui.base.BaseFragment
-import io.github.wulkanowy.ui.modules.about.AboutFragment
 import io.github.wulkanowy.ui.modules.conference.ConferenceFragment
 import io.github.wulkanowy.ui.modules.homework.HomeworkFragment
 import io.github.wulkanowy.ui.modules.luckynumber.LuckyNumberFragment
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/settings/advanced/AdvancedView.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/settings/advanced/AdvancedView.kt
index c2e8e52d..90c0474e 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/settings/advanced/AdvancedView.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/settings/advanced/AdvancedView.kt
@@ -2,4 +2,4 @@ package io.github.wulkanowy.ui.modules.settings.advanced
 
 import io.github.wulkanowy.ui.base.BaseView
 
-interface AdvancedView : BaseView {}
+interface AdvancedView : BaseView
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashActivity.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashActivity.kt
index 2b96a9a0..376ef374 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashActivity.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashActivity.kt
@@ -3,10 +3,8 @@ package io.github.wulkanowy.ui.modules.splash
 import android.os.Bundle
 import android.widget.Toast
 import android.widget.Toast.LENGTH_LONG
-import androidx.appcompat.app.AlertDialog
 import androidx.viewbinding.ViewBinding
 import dagger.hilt.android.AndroidEntryPoint
-import io.github.wulkanowy.R
 import io.github.wulkanowy.ui.base.BaseActivity
 import io.github.wulkanowy.ui.modules.login.LoginActivity
 import io.github.wulkanowy.ui.modules.main.MainActivity
@@ -46,14 +44,4 @@ class SplashActivity : BaseActivity<SplashPresenter, ViewBinding>(), SplashView
     override fun showError(text: String, error: Throwable) {
         Toast.makeText(this, text, LENGTH_LONG).show()
     }
-
-    override fun showKitkatView() {
-        AlertDialog.Builder(this)
-            .setTitle(R.string.drop_kitkat_title)
-            .setMessage(R.string.drop_kitkat_content)
-            .setPositiveButton(android.R.string.ok, null)
-            .setNeutralButton(R.string.drop_kitkat_again) { _, _ -> presenter.onNeutralButtonSelected() }
-            .setOnDismissListener { presenter.onKitkatViewDismissed() }
-            .show()
-    }
 }
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashPresenter.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashPresenter.kt
index 4590d91a..03e43efa 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashPresenter.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashPresenter.kt
@@ -1,12 +1,9 @@
 package io.github.wulkanowy.ui.modules.splash
 
-import android.os.Build
 import io.github.wulkanowy.data.Status
-import io.github.wulkanowy.data.repositories.PreferencesRepository
 import io.github.wulkanowy.data.repositories.StudentRepository
 import io.github.wulkanowy.ui.base.BasePresenter
 import io.github.wulkanowy.ui.base.ErrorHandler
-import io.github.wulkanowy.utils.AppInfo
 import io.github.wulkanowy.utils.flowWithResource
 import kotlinx.coroutines.flow.onEach
 import timber.log.Timber
@@ -15,26 +12,13 @@ import javax.inject.Inject
 class SplashPresenter @Inject constructor(
     errorHandler: ErrorHandler,
     studentRepository: StudentRepository,
-    private val preferencesRepository: PreferencesRepository,
-    private val appInfo: AppInfo
 ) : BasePresenter<SplashView>(errorHandler, studentRepository) {
 
-    private var externalUrl: String? = null
-
     fun onAttachView(view: SplashView, externalUrl: String?) {
         super.onAttachView(view)
-        this.externalUrl = externalUrl
 
-        if (appInfo.systemVersion < Build.VERSION_CODES.LOLLIPOP && !preferencesRepository.isKitkatDialogDisabled) {
-            view.showKitkatView()
-        } else {
-            loadCorrectDataOrUser()
-        }
-    }
-
-    private fun loadCorrectDataOrUser() {
         if (!externalUrl.isNullOrBlank()) {
-            view?.openExternalUrlAndFinish(externalUrl!!)
+            view.openExternalUrlAndFinish(externalUrl)
             return
         }
 
@@ -42,19 +26,11 @@ class SplashPresenter @Inject constructor(
             when (it.status) {
                 Status.LOADING -> Timber.d("Is current user set check started")
                 Status.SUCCESS -> {
-                    if (it.data!!) view?.openMainView()
-                    else view?.openLoginView()
+                    if (it.data!!) view.openMainView()
+                    else view.openLoginView()
                 }
                 Status.ERROR -> errorHandler.dispatch(it.error!!)
             }
         }.launch()
     }
-
-    fun onKitkatViewDismissed() {
-        loadCorrectDataOrUser()
-    }
-
-    fun onNeutralButtonSelected() {
-        preferencesRepository.isKitkatDialogDisabled = true
-    }
 }
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashView.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashView.kt
index c9c5fe9a..a5aa1409 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashView.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/splash/SplashView.kt
@@ -9,6 +9,4 @@ interface SplashView : BaseView {
     fun openMainView()
 
     fun openExternalUrlAndFinish(url: String)
-
-    fun showKitkatView()
 }
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetFactory.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetFactory.kt
index df656c00..7814ff71 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetFactory.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetFactory.kt
@@ -113,7 +113,7 @@ class TimetableWidgetFactory(
         }
     } catch (e: Exception) {
         Timber.e(e, "An error has occurred in timetable widget factory")
-        emptyList<Timetable>()
+        emptyList()
     }
 
     @SuppressLint("DefaultLocale")
diff --git a/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetProvider.kt b/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetProvider.kt
index 071a2d17..fd79f738 100644
--- a/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetProvider.kt
+++ b/app/src/main/java/io/github/wulkanowy/ui/modules/timetablewidget/TimetableWidgetProvider.kt
@@ -230,7 +230,7 @@ class TimetableWidgetProvider : HiltBroadcastReceiver() {
 
     private suspend fun getStudent(studentId: Long, appWidgetId: Int) = try {
         val students = studentRepository.getSavedStudents(false)
-        val student = students.singleOrNull { it -> it.student.id == studentId }?.student
+        val student = students.singleOrNull { it.student.id == studentId }?.student
         when {
             student != null -> student
             studentId != 0L && studentRepository.isCurrentStudentSet() -> {
diff --git a/app/src/main/java/io/github/wulkanowy/utils/security/Scrambler.kt b/app/src/main/java/io/github/wulkanowy/utils/security/Scrambler.kt
index 264f4542..5457a7e7 100644
--- a/app/src/main/java/io/github/wulkanowy/utils/security/Scrambler.kt
+++ b/app/src/main/java/io/github/wulkanowy/utils/security/Scrambler.kt
@@ -58,10 +58,6 @@ private val cipher: Cipher
 fun encrypt(plainText: String, context: Context): String {
     if (plainText.isEmpty()) throw ScramblerException("Text to be encrypted is empty")
 
-    if (SDK_INT < JELLY_BEAN_MR2) {
-        return String(encode(plainText.toByteArray(KEY_CHARSET), DEFAULT), KEY_CHARSET)
-    }
-
     return try {
         if (!isKeyPairExists) generateKeyPair(context)
 
@@ -90,10 +86,6 @@ fun decrypt(cipherText: String): String {
     if (cipherText.isEmpty()) throw ScramblerException("Text to be encrypted is empty")
 
     return try {
-        if (SDK_INT < JELLY_BEAN_MR2 || cipherText.length < 250) {
-            return String(decode(cipherText.toByteArray(KEY_CHARSET), DEFAULT), KEY_CHARSET)
-        }
-
         if (!isKeyPairExists) throw ScramblerException("KeyPair doesn't exist")
 
         cipher.let {
diff --git a/app/src/main/res/layout/fragment_logviewer.xml b/app/src/main/res/layout/fragment_logviewer.xml
index 64f9125f..f8ec37d2 100644
--- a/app/src/main/res/layout/fragment_logviewer.xml
+++ b/app/src/main/res/layout/fragment_logviewer.xml
@@ -29,6 +29,6 @@
         android:focusable="true"
         android:text="@string/logviewer_refresh"
         android:tint="?colorOnSecondary"
-        app:srcCompat="@drawable/ic_refresh" />
-
+        app:srcCompat="@drawable/ic_refresh"
+        tools:ignore="ContentDescription" />
 </androidx.coordinatorlayout.widget.CoordinatorLayout>
diff --git a/app/src/main/res/layout/fragment_mobile_device.xml b/app/src/main/res/layout/fragment_mobile_device.xml
index afe1db8e..e97bd0c5 100644
--- a/app/src/main/res/layout/fragment_mobile_device.xml
+++ b/app/src/main/res/layout/fragment_mobile_device.xml
@@ -111,5 +111,6 @@
         android:layout_gravity="bottom|end"
         android:layout_margin="16dp"
         android:tint="?colorOnSecondary"
-        app:srcCompat="@drawable/ic_all_add" />
+        app:srcCompat="@drawable/ic_all_add"
+        tools:ignore="ContentDescription" />
 </androidx.coordinatorlayout.widget.CoordinatorLayout>
diff --git a/app/src/main/res/layout/item_attendance.xml b/app/src/main/res/layout/item_attendance.xml
index e25b51f6..f3015283 100644
--- a/app/src/main/res/layout/item_attendance.xml
+++ b/app/src/main/res/layout/item_attendance.xml
@@ -52,7 +52,8 @@
             android:layout_height="32dp"
             android:visibility="gone"
             app:srcCompat="@drawable/ic_excuse_waiting"
-            app:tint="?attr/colorOnSurface" />
+            app:tint="?attr/colorOnSurface"
+            tools:ignore="ContentDescription" />
     </LinearLayout>
 
     <androidx.constraintlayout.widget.ConstraintLayout
diff --git a/app/src/main/res/layout/widget_luckynumber_dark.xml b/app/src/main/res/layout/widget_luckynumber_dark.xml
index 77174730..def110de 100644
--- a/app/src/main/res/layout/widget_luckynumber_dark.xml
+++ b/app/src/main/res/layout/widget_luckynumber_dark.xml
@@ -21,7 +21,8 @@
         android:src="@drawable/ic_widget_clover"
         android:tint="@android:color/white"
         android:visibility="gone"
-        tools:visibility="visible" />
+        tools:visibility="visible"
+        tools:ignore="UseAppTint" />
 
     <TextView
         android:id="@+id/luckyNumberWidgetTitle"
@@ -46,7 +47,8 @@
         android:src="@drawable/ic_widget_clover"
         android:tint="@android:color/white"
         android:visibility="gone"
-        tools:visibility="visible" />
+        tools:visibility="visible"
+        tools:ignore="UseAppTint" />
 
     <TextView
         android:id="@+id/luckyNumberWidgetNumber"
diff --git a/app/src/main/res/values-night/styles.xml b/app/src/main/res/values-night/styles.xml
index 68a9fa2f..707fd9ec 100644
--- a/app/src/main/res/values-night/styles.xml
+++ b/app/src/main/res/values-night/styles.xml
@@ -10,44 +10,38 @@
         <item name="colorSwipeRefresh">@color/colorSwipeRefreshDark</item>
         <item name="android:windowBackground">?colorSurface</item>
         <item name="android:textColor">?android:textColorPrimary</item>
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">
-            @color/colorNavigationBarLight
-        </item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">
-            @color/colorStatusBarLight
-        </item>
+        <item name="android:navigationBarColor">@color/colorNavigationBarLight</item>
+        <item name="android:statusBarColor">@color/colorStatusBarLight</item>
         <item name="android:windowLightNavigationBar" tools:targetApi="o_mr1">false</item>
-        <item name="mdtp_theme_dark">true</item>
         <item name="android:windowLightStatusBar" tools:targetApi="m">false</item>
+        <item name="mdtp_theme_dark">true</item>
     </style>
 
     <style name="WulkanowyTheme.Black" parent="WulkanowyTheme.NoActionBar">
         <item name="colorSurface">@android:color/black</item>
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">
-            @color/colorNavigationBarBlack
-        </item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">@color/colorStatusBarBlack</item>
+        <item name="android:navigationBarColor">@color/colorNavigationBarBlack</item>
+        <item name="android:statusBarColor">@color/colorStatusBarBlack</item>
         <item name="android:windowLightStatusBar" tools:targetApi="m">false</item>
     </style>
 
     <style name="WulkanowyTheme.Login" parent="WulkanowyTheme.NoActionBar">
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">?colorSurface</item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">?colorSurface</item>
+        <item name="android:navigationBarColor">?colorSurface</item>
+        <item name="android:statusBarColor">?colorSurface</item>
     </style>
 
     <style name="WulkanowyTheme.Login.Black" parent="WulkanowyTheme.Black">
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">?colorSurface</item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">?colorSurface</item>
+        <item name="android:navigationBarColor">?colorSurface</item>
+        <item name="android:statusBarColor">?colorSurface</item>
     </style>
 
     <style name="WulkanowyTheme.MessageSend" parent="WulkanowyTheme.NoActionBar">
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">?colorSurface</item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">#1C1C1C</item>
+        <item name="android:navigationBarColor">?colorSurface</item>
+        <item name="android:statusBarColor">#1C1C1C</item>
     </style>
 
     <style name="WulkanowyTheme.MessageSend.Black" parent="WulkanowyTheme.Black">
-        <item name="android:navigationBarColor" tools:targetApi="lollipop">?colorSurface</item>
-        <item name="android:statusBarColor" tools:targetApi="lollipop">@android:color/black</item>
+        <item name="android:navigationBarColor">?colorSurface</item>
+        <item name="android:statusBarColor">@android:color/black</item>
     </style>
 
     <style name="WulkanowyTheme.WidgetAccountSwitcher" parent="Theme.MaterialComponents.Dialog">
diff --git a/app/src/main/res/values-v21/styles.xml b/app/src/main/res/values-v21/styles.xml
deleted file mode 100644
index 6b7c7890..00000000
--- a/app/src/main/res/values-v21/styles.xml
+++ /dev/null
@@ -1,13 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-
-    <style name="WulkanowyTheme" parent="BaseWulkanowyTheme">
-        <item name="android:statusBarColor">@android:color/darker_gray</item>
-    </style>
-
-    <style name="WulkanowyTheme.SplashScreen" parent="WulkanowyTheme.NoActionBar">
-        <item name="android:windowBackground">@drawable/layer_splash_background</item>
-        <item name="android:statusBarColor">@color/colorPrimaryDark</item>
-        <item name="android:navigationBarColor">@color/colorPrimaryDark</item>
-    </style>
-</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/preferences_values.xml b/app/src/main/res/values/preferences_values.xml
index 44f54c17..2d2eedb4 100644
--- a/app/src/main/res/values/preferences_values.xml
+++ b/app/src/main/res/values/preferences_values.xml
@@ -109,15 +109,4 @@
         <item>both_semesters</item>
         <item>all_year</item>
     </string-array>
-
-    <string-array name="timetable_show_whole_class_entries">
-        <item>Don\'t show</item>
-        <item>Show all</item>
-        <item>Show smaller</item>
-    </string-array>
-    <string-array name="timetable_show_whole_class_values" translatable="false">
-        <item>no</item>
-        <item>yes</item>
-        <item>small</item>
-    </string-array>
 </resources>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 1b7c9e42..3d54c16a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -40,7 +40,6 @@
     <string name="login_type_hybrid">Hybrid</string>
     <string name="login_token_hint">Token</string>
     <string name="login_pin_hint">PIN</string>
-    <string name="login_api_key_hint">API key</string>
     <string name="login_symbol_hint">Symbol</string>
     <string name="login_sign_in">Sign in</string>
     <string name="login_invalid_password">Password too short</string>
@@ -66,7 +65,6 @@
     <string name="login_contact_email">Email</string>
     <string name="login_contact_discord">Discord</string>
     <string name="login_email_intent_title">Send email</string>
-    <string name="login_email_details">Describe details of problem:</string>
     <string name="login_email_subject" translatable="false">Zgłoszenie: Problemy z logowaniem</string>
     <string name="login_email_text" translatable="false">Informacje o aplikacji:\n\nUrządzenie: %1$s\nWersja SDK: %2$s\nWersja aplikacji: %3$s\nDodatkowe informacje: %4$s\nOstatni błąd: %5$s\n\nOpis problemu: </string>
     <string name="login_recover_warning">Make sure you select the correct UONET+ register variation!</string>
@@ -91,13 +89,10 @@
     <string name="grade_weight">Weight</string>
     <string name="grade_weight_value">Weight: %s</string>
     <string name="grade_comment">Comment</string>
-    <string name="grade_no_new_items">No new grades</string>
     <string name="grade_number_new_items">Number of new ratings: %1$d</string>
     <string name="grade_average">Average: %1$.2f</string>
     <string name="grade_points_sum">Points: %s</string>
     <string name="grade_no_average">No average</string>
-    <string name="grade_predicted">Predicted: %1$s</string>
-    <string name="grade_final">Final: %1$s</string>
     <string name="grade_summary_points">Total points</string>
     <string name="grade_summary_final_grade">Final grade</string>
     <string name="grade_summary_predicted_grade">Predicted grade</string>
@@ -188,10 +183,6 @@
     <string name="attendance_unknown">Unknown</string>
     <string name="attendance_number">Number of lesson</string>
     <string name="attendance_no_items">No entries</string>
-    <plurals name="attendance_number_absences">
-        <item quantity="one">%1$d absence</item>
-        <item quantity="other">%1$d absences</item>
-    </plurals>
     <string name="attendance_excuse_dialog_reason">Absence reason (optional)</string>
     <string name="attendance_excuse_dialog_submit">Send</string>
     <string name="attendance_excuse_success">Absence excuse request sent successfully!</string>
@@ -200,7 +191,6 @@
 
 
     <!--Attendance summary-->
-    <string name="attendance_summary_final">Attendance</string>
     <string name="attendance_summary_total">Total</string>
 
 
@@ -216,7 +206,6 @@
     <string name="message_trash">Trash</string>
     <string name="message_no_subject">(no subject)</string>
     <string name="message_no_items">No messages</string>
-    <string name="message_preview_error">An error occurred while downloading message content</string>
     <string name="message_from">From:</string>
     <string name="message_to">To:</string>
     <string name="message_date">Date: %s</string>
@@ -357,8 +346,6 @@
     <string name="account_logout_student">Student logout</string>
     <string name="account_type_student">Student account</string>
     <string name="account_type_parent">Parent account</string>
-    <string name="account_login_mobile_api">Mobile API mode</string>
-    <string name="account_login_hybrid">Hybrid mode</string>
     <string name="account_details_edit">Edit data</string>
     <string name="account_quick_manager">Accounts manager</string>
     <string name="account_select_student">Select student</string>
@@ -479,7 +466,6 @@
     <string name="pref_view_timetable_show_timers">Mark current lesson</string>
     <string name="pref_view_timetable_show_groups">Show groups next to subjects</string>
     <string name="pref_view_grade_statistics_list">Show chart list in class grades</string>
-    <string name="pref_view_timetable_show_whole_class">Show whole class lessons</string>
     <string name="pref_view_subjects_without_grades">Show subjects without grades</string>
     <string name="pref_view_grade_color_scheme">Grades color scheme</string>
     <string name="pref_view_grade_sorting_mode">Subjects sorting</string>
@@ -532,7 +518,6 @@
 
 
     <!--Notification Channels-->
-    <string name="channel_new_entries">New entries in register</string>
     <string name="channel_new_grades">New grades</string>
     <string name="channel_lucky_number">Lucky number</string>
     <string name="channel_new_message">New messages</string>
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index 08867b79..8fb07e1a 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -11,6 +11,7 @@
         <item name="colorError">@color/colorError</item>
         <item name="colorDivider">@color/colorDivider</item>
         <item name="colorSwipeRefresh">@color/colorSwipeRefresh</item>
+        <item name="android:statusBarColor">@android:color/darker_gray</item>
         <item name="android:textColor">?android:textColorPrimary</item>
         <item name="android:preferenceStyle">@style/PreferenceThemeOverlay</item>
         <item name="mdtp_theme_dark">false</item>
@@ -24,6 +25,8 @@
 
     <style name="WulkanowyTheme.SplashScreen" parent="WulkanowyTheme.NoActionBar">
         <item name="android:windowBackground">@drawable/layer_splash_background</item>
+        <item name="android:statusBarColor">@color/colorPrimaryDark</item>
+        <item name="android:navigationBarColor">@color/colorPrimaryDark</item>
     </style>
 
     <style name="WulkanowyTheme.WidgetAccountSwitcher" parent="Theme.MaterialComponents.Light.Dialog">
diff --git a/app/src/test/java/io/github/wulkanowy/ui/modules/splash/SplashPresenterTest.kt b/app/src/test/java/io/github/wulkanowy/ui/modules/splash/SplashPresenterTest.kt
index 48c2aa9c..98570144 100644
--- a/app/src/test/java/io/github/wulkanowy/ui/modules/splash/SplashPresenterTest.kt
+++ b/app/src/test/java/io/github/wulkanowy/ui/modules/splash/SplashPresenterTest.kt
@@ -1,13 +1,10 @@
 package io.github.wulkanowy.ui.modules.splash
 
 import io.github.wulkanowy.MainCoroutineRule
-import io.github.wulkanowy.data.repositories.PreferencesRepository
 import io.github.wulkanowy.data.repositories.StudentRepository
 import io.github.wulkanowy.ui.base.ErrorHandler
-import io.github.wulkanowy.utils.AppInfo
 import io.mockk.MockKAnnotations
 import io.mockk.coEvery
-import io.mockk.every
 import io.mockk.impl.annotations.MockK
 import io.mockk.verify
 import org.junit.Before
@@ -25,12 +22,6 @@ class SplashPresenterTest {
     @MockK
     lateinit var studentRepository: StudentRepository
 
-    @MockK
-    lateinit var preferencesRepository: PreferencesRepository
-
-    @MockK
-    lateinit var appInfo: AppInfo
-
     @MockK(relaxed = true)
     lateinit var errorHandler: ErrorHandler
 
@@ -39,13 +30,11 @@ class SplashPresenterTest {
     @Before
     fun setUp() {
         MockKAnnotations.init(this)
-        presenter = SplashPresenter(errorHandler, studentRepository, preferencesRepository, appInfo)
+        presenter = SplashPresenter(errorHandler, studentRepository)
     }
 
     @Test
     fun testOpenLoginView() {
-        every { appInfo.systemVersion } returns 30
-        every { preferencesRepository.isKitkatDialogDisabled } returns true
         coEvery { studentRepository.isCurrentStudentSet() } returns false
 
         presenter.onAttachView(splashView, null)
@@ -54,8 +43,6 @@ class SplashPresenterTest {
 
     @Test
     fun testMainMainView() {
-        every { appInfo.systemVersion } returns 30
-        every { preferencesRepository.isKitkatDialogDisabled } returns true
         coEvery { studentRepository.isCurrentStudentSet() } returns true
 
         presenter.onAttachView(splashView, null)