diff --git a/example/lib/main.dart b/example/lib/main.dart
index 99aa6ef..738c81e 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -16,7 +16,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   final String title;
 
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 43a5b55..5463b8a 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -1,62 +1,55 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
-  archive:
-    dependency: transitive
-    description:
-      name: archive
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.11"
-  args:
-    dependency: transitive
-    description:
-      name: args
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.5.2"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.4.0"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.5"
+    version: "2.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.2"
-  collection:
+    version: "1.2.0"
+  clock:
     dependency: transitive
     description:
-      name: collection
-      url: "https://pub.dartlang.org"
+      name: clock
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.14.11"
-  convert:
+    version: "1.1.0"
+  collection:
     dependency: transitive
     description:
-      name: convert
-      url: "https://pub.dartlang.org"
+      name: collection
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.1"
-  crypto:
+    version: "1.15.0"
+  fake_async:
     dependency: transitive
     description:
-      name: crypto
-      url: "https://pub.dartlang.org"
+      name: fake_async
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.3"
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -67,27 +60,20 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  image:
-    dependency: transitive
-    description:
-      name: image
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.1.4"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.12.6"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.8"
+    version: "1.3.0"
   ms_material_color:
     dependency: "direct main"
     description:
@@ -99,30 +85,16 @@ packages:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.6.4"
+    version: "1.8.0"
   pedantic:
     dependency: transitive
     description:
       name: pedantic
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.8.0+1"
-  petitparser:
-    dependency: transitive
-    description:
-      name: petitparser
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.4.0"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.5"
+    version: "1.11.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -132,64 +104,58 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.5.5"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.5"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.11"
+    version: "0.3.0"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.8"
-  xml:
-    dependency: transitive
-    description:
-      name: xml
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "3.5.0"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.6.0 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
+  flutter: ">=1.20.0"
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index ab11f18..0eedab1 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -1,10 +1,12 @@
 name: ms_material_color_example
 description: Ms MaterialColor Demo
+publish_to: none
 
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=1.20.0"
 
 dependencies:
   flutter:
@@ -15,4 +17,4 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
 flutter:
-  uses-material-design: true
\ No newline at end of file
+  uses-material-design: true
diff --git a/pubspec.lock b/pubspec.lock
index 82a349e..0abc2d7 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -5,259 +5,238 @@ packages:
     dependency: transitive
     description:
       name: _fe_analyzer_shared
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.3"
+    version: "21.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.39.4"
+    version: "1.5.0"
   args:
     dependency: transitive
     description:
       name: args
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.5.2"
+    version: "2.1.0"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.4.0"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.5"
+    version: "2.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "1.2.0"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.2"
+    version: "0.3.0"
   collection:
     dependency: transitive
     description:
       name: collection
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.14.11"
+    version: "1.15.0"
   convert:
     dependency: transitive
     description:
       name: convert
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.1"
+    version: "3.0.0"
   coverage:
     dependency: transitive
     description:
       name: coverage
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.13.3+3"
+    version: "1.0.2"
   crypto:
     dependency: transitive
     description:
       name: crypto
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.3"
-  csslib:
+    version: "3.0.1"
+  file:
     dependency: transitive
     description:
-      name: csslib
-      url: "https://pub.dartlang.org"
+      name: file
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.16.1"
+    version: "6.1.0"
   flutter:
     dependency: "direct main"
     description: flutter
     source: sdk
     version: "0.0.0"
-  glob:
+  frontend_server_client:
     dependency: transitive
     description:
-      name: glob
-      url: "https://pub.dartlang.org"
+      name: frontend_server_client
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.2.0"
-  html:
-    dependency: transitive
-    description:
-      name: html
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.14.0+3"
-  http:
+    version: "2.1.0"
+  glob:
     dependency: transitive
     description:
-      name: http
-      url: "https://pub.dartlang.org"
+      name: glob
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.12.0+4"
+    version: "2.0.1"
   http_multi_server:
     dependency: transitive
     description:
       name: http_multi_server
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0"
+    version: "3.0.1"
   http_parser:
     dependency: transitive
     description:
       name: http_parser
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "3.1.3"
+    version: "4.0.0"
   io:
     dependency: transitive
     description:
       name: io
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.3.3"
+    version: "1.0.0"
   js:
     dependency: transitive
     description:
       name: js
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.6.1+1"
+    version: "0.6.3"
   logging:
     dependency: transitive
     description:
       name: logging
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.11.3+2"
+    version: "1.0.1"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.12.6"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.8"
+    version: "1.3.0"
   mime:
     dependency: transitive
     description:
       name: mime
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.9.6+3"
-  multi_server_socket:
-    dependency: transitive
-    description:
-      name: multi_server_socket
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.0.2"
-  node_interop:
-    dependency: transitive
-    description:
-      name: node_interop
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.0.3"
-  node_io:
-    dependency: transitive
-    description:
-      name: node_io
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.1+2"
+    version: "1.0.0"
   node_preamble:
     dependency: transitive
     description:
       name: node_preamble
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.4.8"
+    version: "2.0.0"
   package_config:
     dependency: transitive
     description:
       name: package_config
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.0"
-  package_resolver:
-    dependency: transitive
-    description:
-      name: package_resolver
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.10"
+    version: "2.0.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.6.4"
+    version: "1.8.0"
   pedantic:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: pedantic
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.8.0+1"
+    version: "1.11.0"
   pool:
     dependency: transitive
     description:
       name: pool
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.4.0"
+    version: "1.5.0"
   pub_semver:
     dependency: transitive
     description:
       name: pub_semver
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.4.2"
+    version: "2.0.0"
   shelf:
     dependency: transitive
     description:
       name: shelf
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.7.5"
+    version: "1.1.1"
   shelf_packages_handler:
     dependency: transitive
     description:
       name: shelf_packages_handler
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.4"
+    version: "3.0.0"
   shelf_static:
     dependency: transitive
     description:
       name: shelf_static
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.8"
+    version: "1.0.0"
   shelf_web_socket:
     dependency: transitive
     description:
       name: shelf_web_socket
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.3"
+    version: "1.0.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -267,113 +246,121 @@ packages:
     dependency: transitive
     description:
       name: source_map_stack_trace
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.5"
+    version: "2.1.0"
   source_maps:
     dependency: transitive
     description:
       name: source_maps
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.10.8"
+    version: "0.10.10"
   source_span:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.5.5"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.0.5"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   test:
     dependency: "direct dev"
     description:
       name: test
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.11.0"
+    version: "1.17.3"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.12"
+    version: "0.4.0"
   test_core:
     dependency: transitive
     description:
       name: test_core
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.17"
+    version: "0.3.23"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0"
   vm_service:
     dependency: transitive
     description:
       name: vm_service
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.3.1"
+    version: "6.2.0"
   watcher:
     dependency: transitive
     description:
       name: watcher
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.9.7+13"
+    version: "1.0.0"
   web_socket_channel:
     dependency: transitive
     description:
       name: web_socket_channel
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.1.0"
+    version: "2.1.0"
+  webkit_inspection_protocol:
+    dependency: transitive
+    description:
+      name: webkit_inspection_protocol
+      url: "https://pub.flutter-io.cn"
+    source: hosted
+    version: "1.0.0"
   yaml:
     dependency: transitive
     description:
       name: yaml
-      url: "https://pub.dartlang.org"
+      url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.2.0"
+    version: "3.1.0"
 sdks:
-  dart: ">=2.6.0 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
+  flutter: ">=1.20.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 2700714..5a0f9c6 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,11 +4,13 @@ version: 0.1.0
 homepage: https://github.com/Marcus-Software/ms_material_color
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=1.20.0"
 
 dependencies:
   flutter:
     sdk: flutter
+  pedantic: ^1.11.0
 
 dev_dependencies:
   test: ^1.9.2