diff --git a/IPython/html/static/notebook/less/notebook.less b/IPython/html/static/notebook/less/notebook.less
index 78c3b46..5029729 100644
--- a/IPython/html/static/notebook/less/notebook.less
+++ b/IPython/html/static/notebook/less/notebook.less
@@ -70,6 +70,7 @@ p {
 
 .end_space {
     min-height: 100px;
+    transition: height .2s ease;
 }
 
 .notebook_app #header {
diff --git a/IPython/html/static/style/style.min.css b/IPython/html/static/style/style.min.css
index fa1ff28..8b1e364 100644
--- a/IPython/html/static/style/style.min.css
+++ b/IPython/html/static/style/style.min.css
@@ -10162,6 +10162,7 @@ p {
 }
 .end_space {
   min-height: 100px;
+  transition: height .2s ease;
 }
 .notebook_app #header {
   -webkit-box-shadow: 0px 0px 12px 1px rgba(87, 87, 87, 0.2);