chore(css): increase z-index of site menu class from 1 to 50

BREAKING CHANGE:
To allow for usage of the z-index property for elements in the content area
without the More menu dropdown being displayed behind these elements
the z-index value in the elgg-menu site class has been increased to 50

docs/guides/upgrading.rst

@@ -378,6 +378,14 @@ Elgg's sprites and most of the CSS classes beginning with ``elgg-icon-``
 Usage of ``elgg_view_icon()`` is backward compatible, but static HTML using the ``elgg-icon``
 classes will have to be updated to the new markup.
 
+Increase of z-index value in elgg-menu-site class
+-------------------------------------------------
+
+The value of z-index in the elgg-menu-site class has been increased from 1 to 50 to allow for page elements
+in the content area to use the z-index property without the "More" site menu's dropdown being displayed
+behind these elements. If your plugin/theme overrides the elgg-menu-site class or views/default/elements/navigation.css
+please adjust the z-index value in your modified CSS file accordingly.
+
 Introduced third-party library for sending email
 ------------------------------------------------
 

mod/aalborg_theme/views/default/elements/navigation.css

@@ -177,7 +177,7 @@
 	left: 0;
 	top: 0;
 	position: relative;
-	z-index: 1;
+	z-index: 50;
 }
 .elgg-menu-site > li {
 	float: left;

views/default/elements/navigation.css.php

@@ -164,7 +164,7 @@
 	SITE MENU
 *************************************** */
 .elgg-menu-site {
-	z-index: 1;
+	z-index: 50;
 }
 
 .elgg-menu-site > li > a {