diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 57a5042b..41ffc285 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/calculator_holder"
     android:layout_width="match_parent"
@@ -15,11 +14,11 @@
         android:layout_height="match_parent"
         android:layout_weight="2.1"
         android:fontFamily="sans-serif-light"
-        android:gravity="right|bottom"
+        android:gravity="end|bottom"
         android:maxLines="1"
         android:paddingLeft="@dimen/activity_margin"
         android:paddingRight="@dimen/activity_margin"
-        android:textSize="@dimen/formula_text_size"/>
+        android:textSize="@dimen/formula_text_size" />
 
     <TextView
         android:id="@+id/result"
@@ -27,12 +26,12 @@
         android:layout_height="match_parent"
         android:layout_weight="1.8"
         android:fontFamily="sans-serif-light"
-        android:gravity="center_vertical|right"
+        android:gravity="center_vertical|end"
         android:maxLines="1"
         android:paddingLeft="@dimen/activity_margin"
         android:paddingRight="@dimen/activity_margin"
         android:textSize="@dimen/display_text_size"
-        tools:text="0"/>
+        tools:text="0" />
 
     <LinearLayout
         android:layout_width="match_parent"
@@ -46,7 +45,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="%"/>
+            android:text="%" />
 
         <Button
             android:id="@+id/btn_power"
@@ -54,7 +53,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="^"/>
+            android:text="^" />
 
         <Button
             android:id="@+id/btn_root"
@@ -62,7 +61,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="√"/>
+            android:text="√" />
 
         <Button
             android:id="@+id/btn_clear"
@@ -70,7 +69,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="C"/>
+            android:text="C" />
 
         <Button
             android:id="@+id/btn_reset"
@@ -79,7 +78,7 @@
             android:layout_height="match_parent"
             android:layout_weight="1"
             android:text="AC"
-            android:visibility="gone"/>
+            android:visibility="gone" />
     </LinearLayout>
 
     <LinearLayout
@@ -94,7 +93,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="7"/>
+            android:text="7" />
 
         <Button
             android:id="@+id/btn_8"
@@ -102,7 +101,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="8"/>
+            android:text="8" />
 
         <Button
             android:id="@+id/btn_9"
@@ -110,7 +109,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="9"/>
+            android:text="9" />
 
         <Button
             android:id="@+id/btn_divide"
@@ -118,7 +117,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="÷"/>
+            android:text="÷" />
     </LinearLayout>
 
     <LinearLayout
@@ -133,7 +132,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="4"/>
+            android:text="4" />
 
         <Button
             android:id="@+id/btn_5"
@@ -141,7 +140,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="5"/>
+            android:text="5" />
 
         <Button
             android:id="@+id/btn_6"
@@ -149,7 +148,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="6"/>
+            android:text="6" />
 
         <Button
             android:id="@+id/btn_multiply"
@@ -157,7 +156,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="*"/>
+            android:text="*" />
     </LinearLayout>
 
     <LinearLayout
@@ -172,7 +171,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="1"/>
+            android:text="1" />
 
         <Button
             android:id="@+id/btn_2"
@@ -180,7 +179,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="2"/>
+            android:text="2" />
 
         <Button
             android:id="@+id/btn_3"
@@ -188,7 +187,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="3"/>
+            android:text="3" />
 
         <Button
             android:id="@+id/btn_minus"
@@ -196,7 +195,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="-"/>
+            android:text="-" />
     </LinearLayout>
 
     <LinearLayout
@@ -211,7 +210,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="0"/>
+            android:text="0" />
 
         <Button
             android:id="@+id/btn_decimal"
@@ -219,7 +218,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="."/>
+            android:text="." />
 
         <Button
             android:id="@+id/btn_equals"
@@ -227,7 +226,7 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="="/>
+            android:text="=" />
 
         <Button
             android:id="@+id/btn_plus"
@@ -235,6 +234,6 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_weight="1"
-            android:text="+"/>
+            android:text="+" />
     </LinearLayout>
 </LinearLayout>
diff --git a/app/src/main/res/layout/activity_settings.xml b/app/src/main/res/layout/activity_settings.xml
index b9dbe19c..c3cb61fc 100644
--- a/app/src/main/res/layout/activity_settings.xml
+++ b/app/src/main/res/layout/activity_settings.xml
@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<ScrollView
-    xmlns:android="http://schemas.android.com/apk/res/android"
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/settings_scrollview"
     android:layout_width="match_parent"
@@ -29,7 +28,7 @@
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:paddingStart="@dimen/medium_margin"
-                android:text="@string/purchase_simple_thank_you"/>
+                android:text="@string/purchase_simple_thank_you" />
 
         </RelativeLayout>
 
@@ -50,7 +49,7 @@
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:paddingStart="@dimen/medium_margin"
-                android:text="@string/customize_colors"/>
+                android:text="@string/customize_colors" />
 
         </RelativeLayout>
 
@@ -71,7 +70,7 @@
                 android:layout_height="wrap_content"
                 android:layout_centerVertical="true"
                 android:paddingStart="@dimen/medium_margin"
-                android:text="@string/customize_widget_colors"/>
+                android:text="@string/customize_widget_colors" />
 
         </RelativeLayout>
 
@@ -94,7 +93,7 @@
                 android:clickable="false"
                 android:paddingStart="@dimen/medium_margin"
                 android:text="@string/use_english_language"
-                app:switchPadding="@dimen/medium_margin"/>
+                app:switchPadding="@dimen/medium_margin" />
 
         </RelativeLayout>
 
@@ -117,7 +116,7 @@
                 android:clickable="false"
                 android:paddingStart="@dimen/medium_margin"
                 android:text="@string/vibrate_on_button_press"
-                app:switchPadding="@dimen/medium_margin"/>
+                app:switchPadding="@dimen/medium_margin" />
 
         </RelativeLayout>
 
@@ -140,7 +139,7 @@
                 android:clickable="false"
                 android:paddingStart="@dimen/medium_margin"
                 android:text="@string/prevent_phone_from_sleeping"
-                app:switchPadding="@dimen/medium_margin"/>
+                app:switchPadding="@dimen/medium_margin" />
 
         </RelativeLayout>
     </LinearLayout>
diff --git a/app/src/main/res/layout/widget_config.xml b/app/src/main/res/layout/widget_config.xml
index 72be8993..c1a48ef4 100644
--- a/app/src/main/res/layout/widget_config.xml
+++ b/app/src/main/res/layout/widget_config.xml
@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RelativeLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_centerHorizontal="true"
@@ -13,21 +12,21 @@
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:layout_above="@+id/config_bg_seekbar_holder"
-        android:layout_marginBottom="@dimen/activity_margin"/>
+        android:layout_marginBottom="@dimen/activity_margin" />
 
     <ImageView
         android:id="@+id/config_bg_color"
         android:layout_width="@dimen/widget_colorpicker_size"
         android:layout_height="@dimen/widget_colorpicker_size"
-        android:layout_above="@+id/config_text_color"/>
+        android:layout_above="@+id/config_text_color" />
 
     <RelativeLayout
         android:id="@+id/config_bg_seekbar_holder"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:layout_alignBottom="@+id/config_bg_color"
         android:layout_alignTop="@+id/config_bg_color"
-        android:layout_toRightOf="@+id/config_bg_color"
+        android:layout_alignBottom="@+id/config_bg_color"
+        android:layout_toEndOf="@+id/config_bg_color"
         android:background="@android:color/white">
 
         <SeekBar
@@ -36,27 +35,27 @@
             android:layout_height="wrap_content"
             android:layout_centerVertical="true"
             android:paddingLeft="@dimen/activity_margin"
-            android:paddingRight="@dimen/activity_margin"/>
+            android:paddingRight="@dimen/activity_margin" />
     </RelativeLayout>
 
     <ImageView
         android:id="@+id/config_text_color"
         android:layout_width="@dimen/widget_colorpicker_size"
         android:layout_height="@dimen/widget_colorpicker_size"
-        android:layout_alignParentBottom="true"/>
+        android:layout_alignParentBottom="true" />
 
     <Button
         android:id="@+id/config_save"
         android:layout_width="wrap_content"
         android:layout_height="match_parent"
-        android:layout_alignBottom="@+id/config_text_color"
-        android:layout_alignParentRight="true"
         android:layout_alignTop="@+id/config_text_color"
+        android:layout_alignBottom="@+id/config_text_color"
+        android:layout_alignParentEnd="true"
         android:fontFamily="sans-serif-light"
         android:paddingLeft="@dimen/activity_margin"
         android:paddingRight="@dimen/activity_margin"
         android:text="@string/ok"
         android:textColor="@android:color/white"
-        android:textSize="@dimen/big_text_size"/>
+        android:textSize="@dimen/big_text_size" />
 
 </RelativeLayout>