diff --git a/libs/remix-ui/app/src/lib/remix-app/style/remix-app.css b/libs/remix-ui/app/src/lib/remix-app/style/remix-app.css
index 65508171e4..f7c67ee3cb 100644
--- a/libs/remix-ui/app/src/lib/remix-app/style/remix-app.css
+++ b/libs/remix-ui/app/src/lib/remix-app/style/remix-app.css
@@ -31,7 +31,8 @@ pre {
 .sidepanel           {
   display            : flex;
   flex-direction     : row-reverse;
-  width: 320px;
+  width              : 320px;
+  transition         : width 1s;
 }
 
 .highlightcode       {