diff --git a/src/layouts/Header.less b/src/layouts/Header.less
index 3bd5b52309e086920a5976783541b9eedf09192d..8f5fcb9e4766278df6d30771674056b6acce11b6 100644
--- a/src/layouts/Header.less
+++ b/src/layouts/Header.less
@@ -3,4 +3,5 @@
   top: 0;
   width: 100%;
   z-index: 9;
+  transition: width 0.2s;
 }