diff --git a/app/build.gradle b/app/build.gradle
index c05f792..c1ffb75 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -21,7 +21,7 @@ android {
     }
     defaultConfig {
         applicationId "ch.dissem.apps.${appName.toLowerCase()}"
-        minSdkVersion 19
+        minSdkVersion 21
         targetSdkVersion 27
         versionCode 23
         versionName "1.0-rc1"
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index a9d4f55..81d0586 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -175,20 +175,7 @@
 
         <!-- Receive Wi-Fi connection state changes -->
         <receiver
-            android:name=".listener.WifiReceiver"
-            android:enabled="@bool/is_pre_api_21">
-            <intent-filter>
-                <!-- This is bad for battery life, but needed on older devices to check
-                     if WiFi is available. Let's be honest, the whole app is bad for
-                     battery life. -->
-                <action
-                    android:name="android.net.conn.CONNECTIVITY_CHANGE"
-                    tools:ignore="BatteryLife" />
-            </intent-filter>
-        </receiver>
-        <receiver
-            android:name=".service.StartServiceReceiver"
-            android:enabled="@bool/is_post_api_21">
+            android:name=".service.StartServiceReceiver">
             <intent-filter>
                 <action android:name="android.intent.action.BOOT_COMPLETED" />
             </intent-filter>
diff --git a/app/src/main/java/ch/dissem/apps/abit/MessageDetailActivity.kt b/app/src/main/java/ch/dissem/apps/abit/MessageDetailActivity.kt
index e1c449c..b34fc8b 100644
--- a/app/src/main/java/ch/dissem/apps/abit/MessageDetailActivity.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/MessageDetailActivity.kt
@@ -4,7 +4,6 @@ import android.content.Intent
 import android.os.Bundle
 import android.support.v4.app.NavUtils
 import android.view.MenuItem
-import ch.dissem.bitmessage.entity.Conversation
 import ch.dissem.bitmessage.entity.Plaintext
 
 
diff --git a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
index 3845f8f..7ec83f6 100644
--- a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.kt
@@ -18,8 +18,6 @@ package ch.dissem.apps.abit
 
 import android.app.Activity
 import android.content.*
-import android.os.Build
-import android.os.Build.VERSION_CODES.LOLLIPOP
 import android.os.Bundle
 import android.os.IBinder
 import android.support.v4.app.Fragment
@@ -264,7 +262,7 @@ class SettingsFragment : PreferenceFragmentCompat(), SharedPreferences.OnSharedP
     private fun connectivityChangeListener() =
         OnPreferenceChangeListener { _, _ ->
             context?.let { ctx ->
-                if (Build.VERSION.SDK_INT >= LOLLIPOP && Preferences.isFullNodeActive(ctx)) {
+                if (Preferences.isFullNodeActive(ctx)) {
                     NetworkUtils.scheduleNodeStart(ctx)
                 }
             }
diff --git a/app/src/main/java/ch/dissem/apps/abit/adapter/ConversationAdapter.kt b/app/src/main/java/ch/dissem/apps/abit/adapter/ConversationAdapter.kt
index 2523365..14d4ccc 100644
--- a/app/src/main/java/ch/dissem/apps/abit/adapter/ConversationAdapter.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/adapter/ConversationAdapter.kt
@@ -149,7 +149,7 @@ class ConversationAdapter internal constructor(
             linksClickable = true
             setTextIsSelectable(true)
         }
-        val labelAdapter = LabelAdapter(itemView.context, emptySet<Label>())
+        val labelAdapter = LabelAdapter(itemView.context, emptySet())
         val labels = itemView.findViewById<RecyclerView>(R.id.labels)!!.apply {
             adapter = labelAdapter
             layoutManager = GridLayoutManager(itemView.context, 2)
diff --git a/app/src/main/java/ch/dissem/apps/abit/adapter/LabelAdapter.kt b/app/src/main/java/ch/dissem/apps/abit/adapter/LabelAdapter.kt
index 9d89902..5c39a3f 100644
--- a/app/src/main/java/ch/dissem/apps/abit/adapter/LabelAdapter.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/adapter/LabelAdapter.kt
@@ -2,7 +2,6 @@ package ch.dissem.apps.abit.adapter
 
 import android.content.Context
 import android.content.res.ColorStateList
-import android.os.Build
 import android.support.annotation.ColorInt
 import android.support.v7.widget.RecyclerView
 import android.view.LayoutInflater
@@ -15,7 +14,6 @@ import ch.dissem.apps.abit.util.getIcon
 import ch.dissem.apps.abit.util.getText
 import ch.dissem.bitmessage.entity.valueobject.Label
 import com.mikepenz.iconics.view.IconicsImageView
-import org.jetbrains.anko.backgroundColor
 
 class LabelAdapter internal constructor(private val ctx: Context, labels: Collection<Label>) :
     RecyclerView.Adapter<LabelAdapter.ViewHolder>() {
@@ -50,11 +48,7 @@ class LabelAdapter internal constructor(private val ctx: Context, labels: Collec
         var label = itemView.findViewById<TextView>(R.id.label)!!
 
         fun setBackground(@ColorInt color: Int) {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-                itemView.backgroundTintList = ColorStateList.valueOf(color)
-            } else {
-                itemView.backgroundColor = color
-            }
+            itemView.backgroundTintList = ColorStateList.valueOf(color)
         }
     }
 }
diff --git a/app/src/main/java/ch/dissem/apps/abit/dialog/FullNodeDialogActivity.kt b/app/src/main/java/ch/dissem/apps/abit/dialog/FullNodeDialogActivity.kt
index 98274f3..985d6e4 100644
--- a/app/src/main/java/ch/dissem/apps/abit/dialog/FullNodeDialogActivity.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/dialog/FullNodeDialogActivity.kt
@@ -17,7 +17,6 @@
 package ch.dissem.apps.abit.dialog
 
 import android.app.Activity
-import android.os.Build
 import android.os.Bundle
 import ch.dissem.apps.abit.R
 import ch.dissem.apps.abit.util.NetworkUtils
@@ -37,9 +36,7 @@ class FullNodeDialogActivity : Activity() {
             finish()
         }
         dismiss.setOnClickListener {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-                NetworkUtils.scheduleNodeStart(applicationContext)
-            }
+            NetworkUtils.scheduleNodeStart(applicationContext)
             finish()
         }
     }
diff --git a/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.kt b/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.kt
deleted file mode 100644
index 82851c6..0000000
--- a/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.kt
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- * Copyright 2016 Christian Basler
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package ch.dissem.apps.abit.listener
-
-import android.content.BroadcastReceiver
-import android.content.Context
-import android.content.Intent
-import ch.dissem.apps.abit.service.Singleton
-import ch.dissem.apps.abit.util.NetworkUtils
-import ch.dissem.apps.abit.util.Preferences
-import org.jetbrains.anko.connectivityManager
-
-class WifiReceiver : BroadcastReceiver() {
-    override fun onReceive(ctx: Context, intent: Intent) {
-        if ("android.net.conn.CONNECTIVITY_CHANGE" == intent.action) {
-            val bmc = Singleton.getBitmessageContext(ctx)
-            if (Preferences.isFullNodeActive(ctx) && !bmc.isRunning() && !(Preferences.isWifiOnly(ctx) && ctx.connectivityManager.isActiveNetworkMetered)) {
-                NetworkUtils.doStartBitmessageService(ctx)
-            }
-        }
-    }
-}
diff --git a/app/src/main/java/ch/dissem/apps/abit/service/BitmessageService.kt b/app/src/main/java/ch/dissem/apps/abit/service/BitmessageService.kt
index edc3f87..d22b6fa 100644
--- a/app/src/main/java/ch/dissem/apps/abit/service/BitmessageService.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/service/BitmessageService.kt
@@ -22,7 +22,6 @@ import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
 import android.net.ConnectivityManager
-import android.os.BatteryManager
 import android.os.Handler
 import ch.dissem.apps.abit.notification.NetworkNotification
 import ch.dissem.apps.abit.notification.NetworkNotification.Companion.NETWORK_NOTIFICATION_ID
diff --git a/app/src/main/java/ch/dissem/apps/abit/service/StartupNodeOnWifiService.kt b/app/src/main/java/ch/dissem/apps/abit/service/StartupNodeOnWifiService.kt
index 372393a..0ba1378 100644
--- a/app/src/main/java/ch/dissem/apps/abit/service/StartupNodeOnWifiService.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/service/StartupNodeOnWifiService.kt
@@ -14,7 +14,6 @@ import ch.dissem.apps.abit.util.Preferences
  *
  * And stops it when the preconditions for the job (unmetered network) aren't met anymore.
  */
-@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
 class StartupNodeOnWifiService : JobService() {
     override fun onStartJob(params: JobParameters?): Boolean {
         val bmc = Singleton.getBitmessageContext(this)
diff --git a/app/src/main/java/ch/dissem/apps/abit/synchronization/SyncAdapter.kt b/app/src/main/java/ch/dissem/apps/abit/synchronization/SyncAdapter.kt
index e7c1c84..0bfd678 100644
--- a/app/src/main/java/ch/dissem/apps/abit/synchronization/SyncAdapter.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/synchronization/SyncAdapter.kt
@@ -24,6 +24,7 @@ import ch.dissem.apps.abit.service.Singleton
 import ch.dissem.apps.abit.synchronization.Authenticator.Companion.ACCOUNT_POW
 import ch.dissem.apps.abit.synchronization.Authenticator.Companion.ACCOUNT_SYNC
 import ch.dissem.apps.abit.synchronization.StubProvider.Companion.AUTHORITY
+import ch.dissem.apps.abit.util.NetworkUtils
 import ch.dissem.apps.abit.util.Preferences
 import ch.dissem.bitmessage.exception.DecryptionFailedException
 import ch.dissem.bitmessage.extensions.CryptoCustomMessage
@@ -43,11 +44,11 @@ class SyncAdapter(context: Context, autoInitialize: Boolean) : AbstractThreadedS
     private val bmc = Singleton.getBitmessageContext(context)
 
     override fun onPerformSync(
-            account: Account,
-            extras: Bundle,
-            authority: String,
-            provider: ContentProviderClient,
-            syncResult: SyncResult
+        account: Account,
+        extras: Bundle,
+        authority: String,
+        provider: ContentProviderClient,
+        syncResult: SyncResult
     ) {
         try {
             if (account == ACCOUNT_SYNC) {
@@ -75,16 +76,15 @@ class SyncAdapter(context: Context, autoInitialize: Boolean) : AbstractThreadedS
         }
         val trustedNode = Preferences.getTrustedNode(context)
         if (trustedNode == null) {
-            LOG.info("Trusted node not available, disabling synchronization")
-            stopSync(context)
+            NetworkUtils.scheduleNodeStart(context)
             return
         }
         LOG.info("Synchronization started")
         bmc.synchronize(
-                trustedNode,
-                Preferences.getTrustedNodePort(context),
-                Preferences.getTimeoutInSeconds(context),
-                true
+            trustedNode,
+            Preferences.getTrustedNodePort(context),
+            Preferences.getTimeoutInSeconds(context),
+            true
         )
         LOG.info("Synchronization finished")
     }
@@ -104,7 +104,8 @@ class SyncAdapter(context: Context, autoInitialize: Boolean) : AbstractThreadedS
         // If the Bitmessage context acts as a full node, synchronization isn't necessary
         LOG.info("Looking for completed POW")
 
-        val privateKey = identity.privateKey?.privateEncryptionKey ?: throw IllegalStateException("Identity without private key")
+        val privateKey =
+            identity.privateKey?.privateEncryptionKey ?: throw IllegalStateException("Identity without private key")
         val signingKey = cryptography().createPublicKey(identity.publicDecryptionKey)
         val reader = ProofOfWorkRequest.Reader(identity)
         val powRepo = Singleton.getProofOfWorkRepository(context)
@@ -113,12 +114,13 @@ class SyncAdapter(context: Context, autoInitialize: Boolean) : AbstractThreadedS
             val (objectMessage, nonceTrialsPerByte, extraBytes) = powRepo.getItem(initialHash)
             val target = cryptography().getProofOfWorkTarget(objectMessage, nonceTrialsPerByte, extraBytes)
             val cryptoMsg = CryptoCustomMessage(
-                    ProofOfWorkRequest(identity, initialHash, CALCULATE, target))
+                ProofOfWorkRequest(identity, initialHash, CALCULATE, target)
+            )
             cryptoMsg.signAndEncrypt(identity, signingKey)
             val response = bmc.send(
-                    trustedNode,
-                    Preferences.getTrustedNodePort(context),
-                    cryptoMsg
+                trustedNode,
+                Preferences.getTrustedNodePort(context),
+                cryptoMsg
             )
             if (response.isError) {
                 LOG.error("Server responded with error: ${String(response.getData())}")
diff --git a/app/src/main/java/ch/dissem/apps/abit/util/Assets.kt b/app/src/main/java/ch/dissem/apps/abit/util/Assets.kt
index c09ef2b..3e4465e 100644
--- a/app/src/main/java/ch/dissem/apps/abit/util/Assets.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/util/Assets.kt
@@ -17,8 +17,6 @@
 package ch.dissem.apps.abit.util
 
 import android.content.Context
-import android.support.annotation.DrawableRes
-import android.support.annotation.StringRes
 import ch.dissem.apps.abit.R
 import ch.dissem.bitmessage.entity.Plaintext
 import java.io.IOException
diff --git a/app/src/main/java/ch/dissem/apps/abit/util/NetworkUtils.kt b/app/src/main/java/ch/dissem/apps/abit/util/NetworkUtils.kt
index c401486..8a089fb 100644
--- a/app/src/main/java/ch/dissem/apps/abit/util/NetworkUtils.kt
+++ b/app/src/main/java/ch/dissem/apps/abit/util/NetworkUtils.kt
@@ -6,10 +6,7 @@ import android.app.job.JobScheduler
 import android.content.ComponentName
 import android.content.Context
 import android.content.Intent
-import android.os.Build
-import android.support.annotation.RequiresApi
 import android.support.v4.content.ContextCompat
-import ch.dissem.apps.abit.MainActivity
 import ch.dissem.apps.abit.dialog.FullNodeDialogActivity
 import ch.dissem.apps.abit.service.BitmessageService
 import ch.dissem.apps.abit.service.StartupNodeOnWifiService
@@ -20,36 +17,19 @@ object NetworkUtils {
     fun enableNode(ctx: Context, ask: Boolean = true) {
         Preferences.setFullNodeActive(ctx, true)
 
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-            if (Preferences.isConnectionAllowed(ctx) || !ask) {
-                scheduleNodeStart(ctx)
-            } else {
-                askForConnection(ctx)
-            }
+        if (Preferences.isConnectionAllowed(ctx) || !ask) {
+            scheduleNodeStart(ctx)
         } else {
-            if (Preferences.isWifiOnly(ctx)) {
-                if (Preferences.isConnectionAllowed(ctx)) {
-                    doStartBitmessageService(ctx)
-                    MainActivity.updateNodeSwitch()
-                } else if (ask) {
-                    askForConnection(ctx)
-                }
-            } else {
-                doStartBitmessageService(ctx)
-                MainActivity.updateNodeSwitch()
+            // Ask for connection
+            val dialogIntent = Intent(ctx, FullNodeDialogActivity::class.java)
+            if (ctx !is Activity) {
+                dialogIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+                ctx.sendBroadcast(Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS))
             }
+            ctx.startActivity(dialogIntent)
         }
     }
 
-    private fun askForConnection(ctx: Context) {
-        val dialogIntent = Intent(ctx, FullNodeDialogActivity::class.java)
-        if (ctx !is Activity) {
-            dialogIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
-            ctx.sendBroadcast(Intent(Intent.ACTION_CLOSE_SYSTEM_DIALOGS))
-        }
-        ctx.startActivity(dialogIntent)
-    }
-
     fun doStartBitmessageService(ctx: Context) {
         ContextCompat.startForegroundService(ctx, Intent(ctx, BitmessageService::class.java))
     }
@@ -59,7 +39,6 @@ object NetworkUtils {
         ctx.stopService(Intent(ctx, BitmessageService::class.java))
     }
 
-    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
     fun scheduleNodeStart(ctx: Context) {
         val jobScheduler = ctx.getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobScheduler
         val serviceComponent = ComponentName(ctx, StartupNodeOnWifiService::class.java)
diff --git a/app/src/main/res/drawable-v21/bg_swipe_item_left.xml b/app/src/main/res/drawable-v21/bg_swipe_item_left.xml
deleted file mode 100644
index c5c77fb..0000000
--- a/app/src/main/res/drawable-v21/bg_swipe_item_left.xml
+++ /dev/null
@@ -1,25 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-       Copyright (C) 2015 Haruki Hasegawa
-
-       Licensed under the Apache License, Version 2.0 (the "License");
-       you may not use this file except in compliance with the License.
-       You may obtain a copy of the License at
-
-           http://www.apache.org/licenses/LICENSE-2.0
-
-       Unless required by applicable law or agreed to in writing, software
-       distributed under the License is distributed on an "AS IS" BASIS,
-       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-       See the License for the specific language governing permissions and
-       limitations under the License.
--->
-<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item>
-        <color android:color="@color/bg_swipe_item_trash"/>
-    </item>
-    <item
-        android:drawable="@drawable/ic_item_swipe_trash"
-        android:gravity="right|center_vertical"
-        android:right="16dp"/>
-</layer-list>
diff --git a/app/src/main/res/drawable-v21/bg_swipe_item_right.xml b/app/src/main/res/drawable-v21/bg_swipe_item_right.xml
deleted file mode 100644
index 72bd0b0..0000000
--- a/app/src/main/res/drawable-v21/bg_swipe_item_right.xml
+++ /dev/null
@@ -1,25 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-       Copyright (C) 2015 Haruki Hasegawa
-
-       Licensed under the Apache License, Version 2.0 (the "License");
-       you may not use this file except in compliance with the License.
-       You may obtain a copy of the License at
-
-           http://www.apache.org/licenses/LICENSE-2.0
-
-       Unless required by applicable law or agreed to in writing, software
-       distributed under the License is distributed on an "AS IS" BASIS,
-       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-       See the License for the specific language governing permissions and
-       limitations under the License.
--->
-<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item>
-        <color android:color="@color/bg_swipe_item_archive"/>
-    </item>
-    <item
-        android:drawable="@drawable/ic_item_swipe_archive"
-        android:gravity="left|center_vertical"
-        android:left="16dp"/>
-</layer-list>
diff --git a/app/src/main/res/drawable-v21/material_showcase_button_bg.xml b/app/src/main/res/drawable-v21/material_showcase_button_bg.xml
deleted file mode 100644
index 4df0f4b..0000000
--- a/app/src/main/res/drawable-v21/material_showcase_button_bg.xml
+++ /dev/null
@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-        android:color="#ffffff">
-
-    <item
-            android:id="@android:id/mask"
-            android:drawable="@android:color/white"/>
-
-</ripple>
\ No newline at end of file
diff --git a/app/src/main/res/drawable/bg_swipe_item_left.xml b/app/src/main/res/drawable/bg_swipe_item_left.xml
index 471564e..c5c77fb 100644
--- a/app/src/main/res/drawable/bg_swipe_item_left.xml
+++ b/app/src/main/res/drawable/bg_swipe_item_left.xml
@@ -18,9 +18,8 @@
     <item>
         <color android:color="@color/bg_swipe_item_trash"/>
     </item>
-    <item android:right="16dp">
-        <bitmap
-            android:gravity="right|center_vertical"
-            android:src="@drawable/ic_item_swipe_trash"/>
-    </item>
+    <item
+        android:drawable="@drawable/ic_item_swipe_trash"
+        android:gravity="right|center_vertical"
+        android:right="16dp"/>
 </layer-list>
diff --git a/app/src/main/res/drawable/bg_swipe_item_right.xml b/app/src/main/res/drawable/bg_swipe_item_right.xml
index 22e2b4e..72bd0b0 100644
--- a/app/src/main/res/drawable/bg_swipe_item_right.xml
+++ b/app/src/main/res/drawable/bg_swipe_item_right.xml
@@ -18,9 +18,8 @@
     <item>
         <color android:color="@color/bg_swipe_item_archive"/>
     </item>
-    <item android:left="16dp">
-        <bitmap
-            android:gravity="left|center_vertical"
-            android:src="@drawable/ic_item_swipe_archive"/>
-    </item>
+    <item
+        android:drawable="@drawable/ic_item_swipe_archive"
+        android:gravity="left|center_vertical"
+        android:left="16dp"/>
 </layer-list>
diff --git a/app/src/main/res/drawable/material_showcase_button_bg.xml b/app/src/main/res/drawable/material_showcase_button_bg.xml
index 7171935..4df0f4b 100644
--- a/app/src/main/res/drawable/material_showcase_button_bg.xml
+++ b/app/src/main/res/drawable/material_showcase_button_bg.xml
@@ -1,14 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_pressed="true">
-        <shape android:shape="rectangle">
-            <solid android:color="#ccffffff" />
-        </shape>
-    </item>
-    <item android:state_focused="true">
-        <shape android:shape="rectangle">
-            <stroke android:color="@android:color/white" />
-        </shape>
-    </item>
-    <item android:drawable="@android:color/transparent" />
-</selector>
\ No newline at end of file
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+        android:color="#ffffff">
+
+    <item
+            android:id="@android:id/mask"
+            android:drawable="@android:color/white"/>
+
+</ripple>
\ No newline at end of file
diff --git a/app/src/main/res/layout/showcase_button.xml b/app/src/main/res/layout/showcase_button.xml
deleted file mode 100644
index 2fce3f2..0000000
--- a/app/src/main/res/layout/showcase_button.xml
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Button xmlns:android="http://schemas.android.com/apk/res/android"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:background="@drawable/material_showcase_button_bg"
-        android:text="@string/got_it"
-        android:textAllCaps="true"
-        android:textColor="@android:color/white"
-        android:textSize="13sp"
-        android:textStyle="bold">
-</Button>
diff --git a/app/src/main/res/values-v21/attrs.xml b/app/src/main/res/values-v21/attrs.xml
deleted file mode 100644
index 1c22dab..0000000
--- a/app/src/main/res/values-v21/attrs.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <bool name="is_pre_api_21">false</bool>
-    <bool name="is_post_api_21">true</bool>
-</resources>
diff --git a/app/src/main/res/values/attrs.xml b/app/src/main/res/values/attrs.xml
deleted file mode 100644
index f79595e..0000000
--- a/app/src/main/res/values/attrs.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <bool name="is_pre_api_21">true</bool>
-    <bool name="is_post_api_21">false</bool>
-</resources>
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 32629e5..eeecaad 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -34,7 +34,6 @@
         <SwitchPreferenceCompat
             android:defaultValue="false"
             android:key="require_charging"
-            android:enabled="@bool/is_post_api_21"
             android:summary="@string/require_charging_summary"
             android:title="@string/require_charging" />
         <SwitchPreferenceCompat