diff --git a/app/build.gradle b/app/build.gradle
index d8cc1be..0b6637c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -27,13 +27,13 @@ android {
     }
     defaultConfig {
         applicationId "com.wbrawner.simplemarkdown"
-        minSdkVersion 19
+        minSdkVersion 20
         targetSdkVersion 'Q'
         multiDexEnabled true
         versionCode 18
         versionName "0.6.0"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
-        buildConfigField "boolean", "ENABLE_CUSTOM_CSS", "true"
+        buildConfigField "boolean", "ENABLE_CUSTOM_CSS", "false"
     }
     signingConfigs {
         release {
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 4227bd8..defe2b9 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -67,10 +67,6 @@
                 android:name="android.support.PARENT_ACTIVITY"
                 android:value=".view.activity.MainActivity" />
         </activity>
-        <activity
-            android:name=".view.activity.ExplorerActivity"
-            android:label="@string/title_activity_explorer"
-            android:theme="@style/AppTheme.NoActionBar" />
 
         <meta-data
             android:name="firebase_crashlytics_collection_enabled"
diff --git a/app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt b/app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt
index aeb1aa2..ef6bf4f 100644
--- a/app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt
+++ b/app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt
@@ -37,11 +37,23 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
-
+        setSupportActionBar(toolbar)
+        window.decorView.apply {
+            systemUiVisibility = (
+                    View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
+                            or View.SYSTEM_UI_FLAG_LAYOUT_STABLE
+                            or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+                    )
+//            setOnApplyWindowInsetsListener { v, insets ->
+//                pager.updatePadding(top = insets.systemWindowInsetTop)
+//                insets
+//            }
+        }
         (application as MarkdownApplication).component.inject(this)
         pager.adapter = EditPagerAdapter(supportFragmentManager, this@MainActivity)
         pager.pageMargin = 1
         pager.setPageMarginDrawable(R.color.colorAccent)
+        tabLayout.setupWithViewPager(pager)
         if (resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
             tabLayout!!.visibility = View.GONE
         }
diff --git a/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/EditFragment.kt b/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/EditFragment.kt
index 04008e6..a608e60 100644
--- a/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/EditFragment.kt
+++ b/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/EditFragment.kt
@@ -76,13 +76,13 @@ class EditFragment : Fragment(), MarkdownEditView {
 
     override fun onResume() {
         super.onResume()
-        presenter!!.setEditView(this)
-        markdown = presenter!!.markdown
+        presenter.setEditView(this)
+        markdown = presenter.markdown
     }
 
     override fun onPause() {
         super.onPause()
-        presenter!!.setEditView(null)
+        presenter.setEditView(null)
     }
 
     override fun getMarkdown(): String {
@@ -101,7 +101,7 @@ class EditFragment : Fragment(), MarkdownEditView {
     }
 
     override fun onFileSaved(success: Boolean) {
-        val location = Utils.getDocsPath(activity) + presenter!!.fileName
+        val location = Utils.getDocsPath(activity) + presenter.fileName
         val message: String
         message = if (success) {
             getString(R.string.file_saved, location)
diff --git a/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt b/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt
index c58a0e8..cd9fb2f 100644
--- a/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt
+++ b/app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt
@@ -1,6 +1,8 @@
 package com.wbrawner.simplemarkdown.view.fragment
 
 import android.content.SharedPreferences
+import android.content.res.Configuration.UI_MODE_NIGHT_MASK
+import android.content.res.Configuration.UI_MODE_NIGHT_YES
 import android.os.Bundle
 import android.preference.PreferenceManager
 import android.view.LayoutInflater
@@ -15,6 +17,7 @@ import com.wbrawner.simplemarkdown.presentation.MarkdownPresenter
 import com.wbrawner.simplemarkdown.view.MarkdownPreviewView
 import javax.inject.Inject
 
+
 class PreviewFragment : Fragment(), MarkdownPreviewView {
     @Inject
     lateinit var presenter: MarkdownPresenter
@@ -48,15 +51,18 @@ class PreviewFragment : Fragment(), MarkdownPreviewView {
                 return@post
             }
 
+            val isNightMode = context!!.resources.configuration.uiMode and UI_MODE_NIGHT_MASK == UI_MODE_NIGHT_YES
+            val defaultCssId = if (isNightMode) {
+                R.string.pref_custom_css_default_dark
+            } else {
+                R.string.pref_custom_css_default
+            }
             val css: String? = if (!BuildConfig.ENABLE_CUSTOM_CSS) {
-                sharedPreferences!!.getString(
-                        getString(R.string.pref_custom_css_default),
-                        ""
-                )
+                getString(defaultCssId)
             } else {
                 sharedPreferences!!.getString(
                         getString(R.string.pref_custom_css),
-                        getString(R.string.pref_custom_css_default)
+                        getString(defaultCssId)
                 )
             }
 
diff --git a/app/src/main/res/layout/activity_explorer.xml b/app/src/main/res/layout/activity_explorer.xml
deleted file mode 100644
index ba015e8..0000000
--- a/app/src/main/res/layout/activity_explorer.xml
+++ /dev/null
@@ -1,75 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context="com.wbrawner.simplemarkdown.view.activity.ExplorerActivity">
-
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/toolbarContainer"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:theme="@style/AppTheme.AppBarOverlay"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent">
-
-        <androidx.appcompat.widget.Toolbar
-            android:id="@+id/toolbar"
-            android:layout_width="match_parent"
-            android:layout_height="?attr/actionBarSize"
-            android:background="?attr/colorPrimary"
-            app:popupTheme="@style/AppTheme.PopupOverlay" />
-
-    </com.google.android.material.appbar.AppBarLayout>
-
-    <include
-        android:id="@+id/file_list_container"
-        layout="@layout/content_explorer"
-        android:layout_width="0dp"
-        android:layout_height="0dp"
-        app:layout_constraintBottom_toTopOf="@id/file_name"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@id/toolbarContainer" />
-
-    <com.google.android.material.floatingactionbutton.FloatingActionButton
-        android:id="@+id/fab"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_gravity="bottom|end"
-        android:layout_margin="@dimen/fab_margin"
-        android:layout_marginBottom="8dp"
-        android:layout_marginEnd="8dp"
-        android:visibility="gone"
-        app:layout_constraintBottom_toTopOf="@+id/file_name"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:srcCompat="@android:drawable/ic_input_add" />
-
-    <EditText
-        android:id="@+id/file_name"
-        android:layout_width="0dp"
-        android:layout_height="wrap_content"
-        android:visibility="gone"
-        android:layout_marginBottom="8dp"
-        android:layout_marginEnd="8dp"
-        android:layout_marginStart="8dp"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toStartOf="@+id/button_save"
-        app:layout_constraintStart_toStartOf="parent" />
-
-    <Button
-        android:id="@+id/button_save"
-        style="@style/ButtonRed"
-        android:visibility="gone"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginBottom="8dp"
-        android:layout_marginEnd="8dp"
-        android:text="@string/action_save"
-        android:textAllCaps="true"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent" />
-
-</androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 7f1d0c2..ce72f4d 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -1,14 +1,32 @@
 <?xml version="1.0" encoding="utf-8"?>
-<com.wbrawner.simplemarkdown.view.DisableableViewPager xmlns:android="http://schemas.android.com/apk/res/android"
-    android:id="@+id/pager"
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    android:clipChildren="false"
+    android:fitsSystemWindows="true"
+    android:clipToPadding="false">
+
+    <com.wbrawner.simplemarkdown.view.DisableableViewPager
+        android:id="@+id/pager"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:clipChildren="false"
+        android:fitsSystemWindows="true"
+        android:clipToPadding="false"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/tabLayout" />
 
     <com.google.android.material.tabs.TabLayout
         android:id="@+id/tabLayout"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_gravity="top">
+        android:background="@color/colorBackground"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toTopOf="@+id/toolbar">
 
         <com.google.android.material.tabs.TabItem
             android:id="@+id/editTab"
@@ -22,4 +40,18 @@
             android:layout_height="wrap_content"
             android:text="@string/action_preview" />
     </com.google.android.material.tabs.TabLayout>
-</com.wbrawner.simplemarkdown.view.DisableableViewPager>
+
+    <androidx.appcompat.widget.Toolbar
+        android:id="@+id/toolbar"
+        android:background="@color/colorBackground"
+        android:layout_width="match_parent"
+        android:layout_height="?attr/actionBarSize"
+        android:clipChildren="false"
+        android:fitsSystemWindows="true"
+        android:clipToPadding="false"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent" />
+
+
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_settings.xml b/app/src/main/res/layout/activity_settings.xml
index 684a1f8..e64a999 100644
--- a/app/src/main/res/layout/activity_settings.xml
+++ b/app/src/main/res/layout/activity_settings.xml
@@ -2,7 +2,7 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    xmlns:app="http://schemas.android.com/apk/res-auto">
+    android:fitsSystemWindows="true">
     <fragment
         android:id="@+id/fragment_settings"
         android:layout_width="match_parent"
diff --git a/app/src/main/res/values-night/colors.xml b/app/src/main/res/values-night/colors.xml
new file mode 100644
index 0000000..f001f52
--- /dev/null
+++ b/app/src/main/res/values-night/colors.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorBackground">#000000</color>
+</resources>
diff --git a/app/src/main/res/values/colors.xml b/app/src/main/res/values/colors.xml
index 65687cf..8f521e5 100644
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -3,4 +3,5 @@
     <color name="colorPrimary">#d32f2f</color>
     <color name="colorPrimaryDark">#b71c1c</color>
     <color name="colorAccent">#d32f2f</color>
+    <color name="colorBackground">#FFFFFF</color>
 </resources>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 19ee33d..37ee8e6 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -56,6 +56,8 @@
     <string name="pref_title_custom_css">Custom CSS</string>
     <string name="pref_description_custom_css">Paste or write your own CSS to be used for the preview pane</string>
     <string name="pref_custom_css_default" translatable="false">pre {overflow:scroll; padding:15px; background: #F1F1F1;}</string>
+    <string name="pref_custom_css_default_dark" translatable="false">body{background:
+        #000000;color: #F1F1F1;}a{color:#7b91ff;}pre{background:#111111;}</string>
     <string-array name="pref_entries_default_view">
         <item>@string/value_edit_view</item>
         <item>@string/value_explorer_view</item>
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index f3b0791..97bf018 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -1,29 +1,15 @@
 <resources>
 
     <!-- Base application theme. -->
-    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+    <style name="AppTheme" parent="Theme.AppCompat.DayNight.NoActionBar">
         <!-- Customize your theme here. -->
         <item name="colorPrimary">@color/colorPrimary</item>
         <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
         <item name="colorAccent">@color/colorAccent</item>
+        <item name="android:windowTranslucentStatus">true</item>
     </style>
 
     <style name="AppTheme.Splash" parent="AppTheme">
         <item name="android:windowBackground">@drawable/splash_bg</item>
     </style>
-
-    <style name="AppTheme.NoActionBar">
-        <item name="windowActionBar">false</item>
-        <item name="windowNoTitle">true</item>
-    </style>
-
-    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
-
-    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
-
-    <style name="ButtonRed">
-        <item name="android:background">@color/colorAccent</item>
-        <item name="android:textColor">#FFFFFF</item>
-    </style>
-
 </resources>