diff --git a/public/stylesheets/educoder/edu-main.css b/public/stylesheets/educoder/edu-main.css
index 79385ef4..5a4d2c48 100644
--- a/public/stylesheets/educoder/edu-main.css
+++ b/public/stylesheets/educoder/edu-main.css
@@ -1016,6 +1016,10 @@ html>body #ajax-indicator { position: fixed; }
     white-space: nowrap;
     overflow: hidden;
     text-overflow: ellipsis;
+    transition: max-width .2s;
+    -moz-transition: max-width .2s; /* Firefox 4 */
+    -webkit-transition: max-width .2s; /* Safari 和 Chrome */
+    -o-transition: max-width .2s; /* Opera */
 }
 .project-package-item .item-head-tags {
     display: -webkit-flex;