force portrait orientation

app/src/main/AndroidManifest.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest package="calendar.simplemobiletools.com"
-          xmlns:android="http://schemas.android.com/apk/res/android">
+<manifest
+    package="calendar.simplemobiletools.com"
+    xmlns:android="http://schemas.android.com/apk/res/android">
 
     <application
         android:allowBackup="true"
@@ -8,7 +9,9 @@
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".MainActivity">
+        <activity
+            android:name=".MainActivity"
+            android:screenOrientation="portrait">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>