Merge pull request #5004 from jdfreder/widget-vslider-spacing

Fix widget vslider spacing

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

@@ -223,17 +223,20 @@
 
 .widget-hbox-single {
     /* Single line horizontal widgets */
+    .widget-hbox();
     height : 30px;
+}
 
-    .widget-hbox();
+.widget-vbox {
+    /* Vertical widgets */ 
+    .widget-box();
+    .vbox();
 }
 
 .widget-vbox-single {
     /* For vertical slides */ 
+    .widget-vbox();
     width : 30px;
-
-    .widget-box();
-    .vbox();
 }
 
 .widget-modal {