Merge pull request #644 from dalf/logicodev_fix

[fix] close #637 : the search box doesn't overlap the menu.

searx/static/themes/oscar/less/logicodev/navbar.less

         padding: 0 30px;
         margin: 0;
     }
-    z-index: 1;
+    z-index: 10;
 }
 
 // Hover color