diff --git a/lib/model/note.dart b/lib/model/note.dart
index b6b1e6b..7ad3974 100644
--- a/lib/model/note.dart
+++ b/lib/model/note.dart
@@ -15,11 +15,9 @@ enum NoteState { Normal, Archived, Trashed }
 enum NoteSort { Title, LastModified }
 
 @immutable
-/**
- * Represents a note file.
- *
- * The file name is always in the form `<title>.<tags>.<state>.<extension>`.
- */
+/// Represents a note file.
+///
+/// The file name is always in the form `<title>.<tags>.<state>.<extension>`.
 class Note {
   final File file;
   final List<String> _basenameParts;
diff --git a/lib/route/main.dart b/lib/route/main.dart
index 7b01481..7598c56 100644
--- a/lib/route/main.dart
+++ b/lib/route/main.dart
@@ -96,7 +96,7 @@ class _MainScreenState extends State<MainScreen> {
                       onPressed: () {
                         final snackBar =
                             SnackBar(content: Text('Create new file.'));
-                        Scaffold.of(context).showSnackBar(snackBar);
+                        ScaffoldMessenger.of(context).showSnackBar(snackBar);
                       },
                       label: Text('New draft'.toUpperCase()),
                       icon: Icon(TxtIcons.add),
diff --git a/lib/route/themes.dart b/lib/route/themes.dart
index 5ae56b4..454bb91 100644
--- a/lib/route/themes.dart
+++ b/lib/route/themes.dart
@@ -75,7 +75,7 @@ class _ColorSchemeCard extends StatelessWidget {
     this.subtitle,
     this.description,
     this.icon,
-  });
+  }) : super(key: key);
 
   _isThemeSelected(BuildContext context) {
     return AppTheme.of(context).colorScheme == colorScheme;
@@ -108,7 +108,7 @@ class _ColorSchemeCard extends StatelessWidget {
               padding: EdgeInsets.only(bottom: 16, left: 16, right: 16),
               child: Text(
                 subtitle,
-                style: Theme.of(context).textTheme.subtitle,
+                style: Theme.of(context).textTheme.subtitle2,
               ),
             ),
           );
@@ -119,7 +119,7 @@ class _ColorSchemeCard extends StatelessWidget {
               padding: EdgeInsets.only(bottom: 16, left: 16, right: 16),
               child: Text(
                 description,
-                style: Theme.of(context).textTheme.body1,
+                style: Theme.of(context).textTheme.bodyText2,
               ),
             ),
           );
diff --git a/lib/widget/stadium_border_notched_rectangle.dart b/lib/widget/stadium_border_notched_rectangle.dart
index c397b9d..1df7807 100644
--- a/lib/widget/stadium_border_notched_rectangle.dart
+++ b/lib/widget/stadium_border_notched_rectangle.dart
@@ -50,27 +50,30 @@ class StadiumBorderNotchedRectangle implements NotchedShape {
     final double p2yA = sqrt(r * r - p2xA * p2xA);
     final double p2yB = sqrt(r * r - p2xB * p2xB);
 
-    final List<Offset> p = List<Offset>(6);
-
     // p0, p1, and p2 are the control points for segment A.
-    p[0] = Offset(a - s1, b);
-    p[1] = Offset(a, b);
-    final double cmp = b < 0 ? -1.0 : 1.0;
-    p[2] = cmp * p2yA > cmp * p2yB ? Offset(p2xA, p2yA) : Offset(p2xB, p2yB);
+    Offset p0 = Offset(a - s1, b);
+    Offset p1 = Offset(a, b);
+    double cmp = b < 0 ? -1.0 : 1.0;
+    Offset p2 = cmp * p2yA > cmp * p2yB ? Offset(p2xA, p2yA) : Offset(p2xB, p2yB);
 
     // p3, p4, and p5 are the control points for segment B, which is a mirror
     // of segment A around the y axis.
-    p[3] = Offset(-1.0 * p[2].dx, p[2].dy);
-    p[4] = Offset(-1.0 * p[1].dx, p[1].dy);
-    p[5] = Offset(-1.0 * p[0].dx, p[0].dy);
+    Offset p3 = Offset(-1.0 * p2.dx, p2.dy);
+    Offset p4 = Offset(-1.0 * p1.dx, p1.dy);
+    Offset p5 = Offset(-1.0 * p0.dx, p0.dy);
 
     // translate all points back to the absolute coordinate system.
-    for (int i = 0; i < p.length; i += 1) p[i] += guest.center;
+    p0 += guest.center;
+    p1 += guest.center;
+    p2 += guest.center;
+    p3 += guest.center;
+    p4 += guest.center;
+    p5 += guest.center;
 
     return Path()
       ..moveTo(host.left, host.top)
-      ..lineTo(p[0].dx, p[0].dy)
-      ..quadraticBezierTo(p[1].dx, p[1].dy, p[2].dx, p[2].dy)
+      ..lineTo(p0.dx, p0.dy)
+      ..quadraticBezierTo(p1.dx, p1.dy, p2.dx, p2.dy)
       ..arcToPoint(
         guest.bottomLeft + Offset(guest.height / 2, 0),
         radius: Radius.circular(guest.height / 2),
@@ -78,11 +81,11 @@ class StadiumBorderNotchedRectangle implements NotchedShape {
       )
       ..lineTo(guest.right - guest.height / 2, guest.bottom)
       ..arcToPoint(
-        p[3],
+        p3,
         radius: Radius.circular(guest.height / 2),
         clockwise: false,
       )
-      ..quadraticBezierTo(p[4].dx, p[4].dy, p[5].dx, p[5].dy)
+      ..quadraticBezierTo(p4.dx, p4.dy, p5.dx, p5.dy)
       ..lineTo(host.right, host.top)
       ..lineTo(host.right, host.bottom)
       ..lineTo(host.left, host.bottom)