minor UI adjustment

app/src/main/res/layout/activity_create_content.xml

@@ -40,6 +40,7 @@
             android:layout_width="240dp"
             android:layout_height="wrap_content"
             android:layout_below="@id/appbar"
+            android:layout_margin="16dp"
             android:hint="@string/subject">
 
             <android.support.design.widget.TextInputEditText
@@ -52,6 +53,8 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_below="@id/subject_input"
+            android:layout_marginStart="16dp"
+            android:layout_marginEnd="16dp"
             app:hint="topic message"/>
 
         <gr.thmmy.mthmmy.editorview.EmojiKeyboard