diff --git a/IPython/html/static/notebook/less/textcell.less b/IPython/html/static/notebook/less/textcell.less
index bacb486df..ee125e5ad 100644
--- a/IPython/html/static/notebook/less/textcell.less
+++ b/IPython/html/static/notebook/less/textcell.less
@@ -36,7 +36,6 @@ div.cell.text_cell.rendered {
     padding: 0px;
 }
 
-
 .text_cell.rendered .input_area {
     display: none;
 }
@@ -45,25 +44,25 @@ div.cell.text_cell.rendered {
     display:none;
 }
 
-.cm-s-heading-1,
-.cm-s-heading-2,
-.cm-s-heading-3,
-.cm-s-heading-4,
-.cm-s-heading-5,
-.cm-s-heading-6 {
+.cm-header-1,
+.cm-header-2,
+.cm-header-3,
+.cm-header-4,
+.cm-header-5,
+.cm-header-6 {
     font-weight: bold;
     font-family: @font-family-sans-serif;
 }
 
-.cm-s-heading-1 { font-size:150%; }
-.cm-s-heading-2 { font-size: 130%; }
-.cm-s-heading-3 { font-size: 120%; }
-.cm-s-heading-4 { font-size: 110%; }
-.cm-s-heading-5 {
-    font-size: 100%; 
+.cm-header-1 { font-size: 185.7%; }
+.cm-header-2 { font-size: 157.1%; }
+.cm-header-3 { font-size: 128.6%; }
+.cm-header-4 { font-size: 110%; }
+.cm-header-5 {
+    font-size: 100%;
     font-style: italic;
 }
-.cm-s-heading-6 {
-    font-size: 90%; 
+.cm-header-6 {
+    font-size: 100%;
     font-style: italic;
 }
diff --git a/IPython/html/static/style/ipython.min.css b/IPython/html/static/style/ipython.min.css
index fa2d6bfb0..ee5e7401e 100644
--- a/IPython/html/static/style/ipython.min.css
+++ b/IPython/html/static/style/ipython.min.css
@@ -1116,33 +1116,33 @@ div.cell.text_cell.rendered {
 .text_cell.unrendered .text_cell_render {
   display: none;
 }
-.cm-s-heading-1,
-.cm-s-heading-2,
-.cm-s-heading-3,
-.cm-s-heading-4,
-.cm-s-heading-5,
-.cm-s-heading-6 {
+.cm-header-1,
+.cm-header-2,
+.cm-header-3,
+.cm-header-4,
+.cm-header-5,
+.cm-header-6 {
   font-weight: bold;
   font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
 }
-.cm-s-heading-1 {
-  font-size: 150%;
+.cm-header-1 {
+  font-size: 185.7%;
 }
-.cm-s-heading-2 {
-  font-size: 130%;
+.cm-header-2 {
+  font-size: 157.1%;
 }
-.cm-s-heading-3 {
-  font-size: 120%;
+.cm-header-3 {
+  font-size: 128.6%;
 }
-.cm-s-heading-4 {
+.cm-header-4 {
   font-size: 110%;
 }
-.cm-s-heading-5 {
+.cm-header-5 {
   font-size: 100%;
   font-style: italic;
 }
-.cm-s-heading-6 {
-  font-size: 90%;
+.cm-header-6 {
+  font-size: 100%;
   font-style: italic;
 }
 .widget-area {
diff --git a/IPython/html/static/style/style.min.css b/IPython/html/static/style/style.min.css
index bdddd754b..600c2ddf8 100644
--- a/IPython/html/static/style/style.min.css
+++ b/IPython/html/static/style/style.min.css
@@ -8985,33 +8985,33 @@ div.cell.text_cell.rendered {
 .text_cell.unrendered .text_cell_render {
   display: none;
 }
-.cm-s-heading-1,
-.cm-s-heading-2,
-.cm-s-heading-3,
-.cm-s-heading-4,
-.cm-s-heading-5,
-.cm-s-heading-6 {
+.cm-header-1,
+.cm-header-2,
+.cm-header-3,
+.cm-header-4,
+.cm-header-5,
+.cm-header-6 {
   font-weight: bold;
   font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
 }
-.cm-s-heading-1 {
-  font-size: 150%;
+.cm-header-1 {
+  font-size: 185.7%;
 }
-.cm-s-heading-2 {
-  font-size: 130%;
+.cm-header-2 {
+  font-size: 157.1%;
 }
-.cm-s-heading-3 {
-  font-size: 120%;
+.cm-header-3 {
+  font-size: 128.6%;
 }
-.cm-s-heading-4 {
+.cm-header-4 {
   font-size: 110%;
 }
-.cm-s-heading-5 {
+.cm-header-5 {
   font-size: 100%;
   font-style: italic;
 }
-.cm-s-heading-6 {
-  font-size: 90%;
+.cm-header-6 {
+  font-size: 100%;
   font-style: italic;
 }
 .widget-area {