Address comments

IPython/html/static/style/ipython.less

@@ -2,6 +2,9 b''
 @import "../components/bootstrap/less/variables.less";
 @import "../components/bootstrap/less/mixins.less";
 
+// minimal imports from font-awesome
+@import "../components/font-awesome/less/variables.less";
+
 // base
 @import "../base/less/style.less";
 

IPython/html/static/widgets/less/widgets.less

@@ -28,15 +28,12 b''
     }
 
     &.connection-problems .prompt:after {
-        content: '\f127';
+        content: @fa-var-chain-broken;
         font-family: 'FontAwesome';
         color: @brand-danger;
-        padding: 4px;
-        position: relative;
-        border-radius: 2px;
-        font-size: 14px;
-        left: 0px;
+        font-size: @notebook_font_size;
         top: 3px;
+        padding: 3px;
     }
 }