diff --git a/IPython/html/static/notebook/less/outputarea.less b/IPython/html/static/notebook/less/outputarea.less
index 4b5738d..3312321 100644
--- a/IPython/html/static/notebook/less/outputarea.less
+++ b/IPython/html/static/notebook/less/outputarea.less
@@ -1,7 +1,9 @@
 div.output_wrapper {
     /* this position must be relative to enable descendents to be absolute within it */
     position: relative;
-    .vbox()
+    .vbox();
+    // avoid scrolled output overlaying input in some strange circumstances
+    z-index: 1;
 }
 
 /* class for the output area when it should be height-limited */
diff --git a/IPython/html/static/style/ipython.min.css b/IPython/html/static/style/ipython.min.css
index 38af689..e590069 100644
--- a/IPython/html/static/style/ipython.min.css
+++ b/IPython/html/static/style/ipython.min.css
@@ -747,6 +747,7 @@ div.output_wrapper {
   display: flex;
   flex-direction: column;
   align-items: stretch;
+  z-index: 1;
 }
 /* class for the output area when it should be height-limited */
 div.output_scroll {
diff --git a/IPython/html/static/style/style.min.css b/IPython/html/static/style/style.min.css
index e043bc8..56d6f31 100644
--- a/IPython/html/static/style/style.min.css
+++ b/IPython/html/static/style/style.min.css
@@ -9536,6 +9536,7 @@ div.output_wrapper {
   display: flex;
   flex-direction: column;
   align-items: stretch;
+  z-index: 1;
 }
 /* class for the output area when it should be height-limited */
 div.output_scroll {