diff --git a/IPython/frontend/html/notebook/static/css/notebook.less b/IPython/frontend/html/notebook/static/css/notebook.less
index 595d66e..13b5f8e 100644
--- a/IPython/frontend/html/notebook/static/css/notebook.less
+++ b/IPython/frontend/html/notebook/static/css/notebook.less
@@ -6,7 +6,6 @@
 
 @import "variables.less";
 
-
 body {
     overflow: hidden;
 }
@@ -153,7 +152,7 @@ div.ui-widget-content {
     border: 1px solid transparent;
 
     &.selected {
-        border-radius: @corner_radius;
+        .corner-all;
         background-color:@cell_selected_background;
         border : thin @border_color solid;
     }
@@ -194,7 +193,7 @@ div.input {
 div.input_area {
     color: black;
     border: 1px solid @border_color;
-    border-radius: @corner_radius;
+    .corner-all;
     background: @cell_background;
 }
 
@@ -221,7 +220,7 @@ div.output_scroll {
   width: 100%;
   
   overflow: auto;
-  border-radius: @corner_radius;
+  .corner-all;
   box-shadow: inset 0 2px 8px rgba(0, 0, 0, .8);
 }
 
@@ -234,7 +233,7 @@ div.out_prompt_overlay {
   height: 100%;
   padding: 0px;
   position: absolute;
-  border-radius: @corner_radius;
+  .corner-all;
 }
 
 div.out_prompt_overlay:hover {
@@ -320,7 +319,7 @@ div.text_cell {
 div.text_cell_input {
     color: black;
     border: 1px solid @border_color;
-    border-radius: @corner_radius;
+    .corner-all;
     background: @cell_background;
 }
 
@@ -411,7 +410,7 @@ option.introspection {
 pre.dialog {
     background-color: @cell_background;
     border: 1px solid #ddd;
-    border-radius: @corner_radius;
+    .corner-all;
     padding: 0.4em;
     padding-left: 2em;
 }
@@ -442,3 +441,7 @@ pre, code, kbd, samp { white-space: pre-wrap; }
 .js-error {
     color: darkred;
 }
+
+
+
+
diff --git a/IPython/frontend/html/notebook/static/css/variables.less b/IPython/frontend/html/notebook/static/css/variables.less
index b043c46..a7585a1 100644
--- a/IPython/frontend/html/notebook/static/css/variables.less
+++ b/IPython/frontend/html/notebook/static/css/variables.less
@@ -3,3 +3,13 @@
 @cell_selected_background: darken(@notebook_background, 2%);
 @cell_background: darken(@notebook_background, 3.2%);
 @border_color: darken(@cell_selected_background, 10%);
+
+
+
+
+
+// utilities mixins 
+
+.corner-all {
+    border-radius:@corner_radius;
+}
diff --git a/IPython/frontend/html/notebook/templates/notebook.html b/IPython/frontend/html/notebook/templates/notebook.html
index dd45862..c6f6a0b 100644
--- a/IPython/frontend/html/notebook/templates/notebook.html
+++ b/IPython/frontend/html/notebook/templates/notebook.html
@@ -174,7 +174,7 @@ data-notebook-id={{notebook_id}}
     </div>
 
 </div>
-<div id='tooltip' class='ipython_tooltip ui-corner-all' style='display:none'></div>
+<div id='tooltip' class='ipython_tooltip corner-all' style='display:none'></div>
 
 
 {% endblock %}