OO-533 translucent pool image, fix menu indent

src/main/webapp/static/themes/openolat/all/modules/_nav.scss

@@ -218,7 +218,9 @@ div.b_tree {
 		margin: 0 0 0 $tree_level_margin; 
 		ul { 
 			padding: 0;
-			margin: 0 0 0 0;
+			&.b_tree_l0 {
+				margin-left: 0;
+			}
 		} 		
 	}