diff --git a/README.md b/README.md
index 3ff4afe..3c1f945 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ This is a simple calendar widget.
 
 ## introduce
 
-![](https://github.com/zeqinjie/tw_calendar/blob/main/assets/1.gif)
+![](https://github.com/zeqinjie/tw_calendar/blob/main/assets/1.gif?raw=true)
 
 
 ## Installing
diff --git a/pubspec.yaml b/pubspec.yaml
index 5e3a77c..917c624 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,7 +4,7 @@ version: 2.0.0
 homepage: https://github.com/zeqinjie/tw_calendar
 
 environment:
-  sdk: ">=2.12.0 <3.0.0"
+  sdk: ">=2.12.0 <4.0.0"
 
 dependencies:
   flutter: