Move header padding removal to base page style

IPython/html/static/base/less/page.less

@@ -20,6 +20,7 b' body {'
 div#header {
     /* Initially hidden to prevent FLOUC */
     display: none;
+    margin-bottom: 0px;
 }
 
 #ipython_notebook {

IPython/html/static/notebook/less/menubar.less

@@ -30,4 +30,8 b' ul#help_menu li a{'
     i {
         margin-right: -1.2em;
     }
-}
  No newline at end of file
+}
+
+ul#menus {
+  float: left;
+}

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

@@ -75,7 +75,3 b' p {'
 .end_space {
     height: 200px;
 }
-
-#header {
-    margin-bottom: 0px;
-}