Fix scrolling over sidenav

Summary: This is the simplest fix I could find.

Test Plan: Scroll over sidenav on home, maniphest, workboards, etc. Test mobile, deskop. Firefox, Safari, Chrome, Internet Explorer.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11881

resources/celerity/map.php

@@ -7,7 +7,7 @@
  */
 return array(
   'names' => array(
-    'core.pkg.css' => '0b9ca9d2',
+    'core.pkg.css' => 'ba9b6450',
     'core.pkg.js' => '23d653bb',
     'darkconsole.pkg.js' => '8ab24e01',
     'differential.pkg.css' => '380f07e5',
@@ -107,7 +107,7 @@ return array(
     'rsrc/css/core/core.css' => '8f9b9588',
     'rsrc/css/core/remarkup.css' => 'e8e5a324',
     'rsrc/css/core/syntax.css' => '56c1ba38',
-    'rsrc/css/core/z-index.css' => '7ec93336',
+    'rsrc/css/core/z-index.css' => '8239495e',
     'rsrc/css/diviner/diviner-shared.css' => '38813222',
     'rsrc/css/font/font-awesome.css' => 'ae9a7b4d',
     'rsrc/css/font/font-source-sans-pro.css' => '0d859f60',
@@ -760,7 +760,7 @@ return array(
     'phabricator-uiexample-reactor-select' => 'a155550f',
     'phabricator-uiexample-reactor-sendclass' => '1def2711',
     'phabricator-uiexample-reactor-sendproperties' => 'b1f0ccee',
-    'phabricator-zindex-css' => '7ec93336',
+    'phabricator-zindex-css' => '8239495e',
     'phame-css' => 'db5682e3',
     'pholio-css' => '95174bdd',
     'pholio-edit-css' => '3ad9d1ee',

webroot/rsrc/css/core/z-index.css

@@ -2,6 +2,10 @@
  * @provides phabricator-zindex-css
  */
 
+.phabricator-nav-column-background {
+  z-index: -1;
+}
+
 .keyboard-focus-focus-reticle {
   z-index: 1;
 }
@@ -34,10 +38,6 @@
   z-index: 3;
 }
 
-.phabricator-nav-column-background {
-  z-index: 3;
-}
-
 .phui-crumbs-view {
   z-index: 3;
 }