OO-1211

replaced dmz bg margins with background-position

src/main/webapp/static/themes/light/_config.scss

@@ -82,6 +82,7 @@ $o-main-right-bg	: inherit !default;
 
 /* Page main navigation for sites, tabs and tools */
 $o-navbar-height					: $navbar-height !default;
+$o-navbar-dmz-height				: $navbar-height !default;
 $o-navbar-z-index					: 4 !default;
 $o-navbar-margin-bottom				: $navbar-margin-bottom !default;
 $o-navbar-padding-horizontal		: $navbar-padding-horizontal !default;

src/main/webapp/static/themes/light/modules/_dmz.scss

@@ -6,8 +6,6 @@ body.o_dmz {
 		left: 0;
 		width: 100%;
 		height: 100%;
-		margin-top: $o-navbar-height;
-		margin-bottom: $o-footer-height;
 	
 		/* background gradient depending on login box positioning */
 		$o-login-bg-gradient-to : right;	
@@ -19,6 +17,7 @@ body.o_dmz {
 		}
 		background: linear-gradient(to $o-login-bg-gradient-to, $o-login-form-bg-gradient-steps...), url('#{$o-login-form-bg-img}');
 		background-size: cover, cover;
+		background-position: 0px $o-navbar-dmz-height, 0px $o-navbar-dmz-height;
 	}
 
 	#o_main_wrapper, #o_main_wrapper #o_main_container {