Added missing css class

resources/templates/dashboard/pager_header.twig

@@ -18,7 +18,7 @@
                 <button class="btn btn-outline-primary dropdown-toggle" type="button" id="dropdownOrder" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                     {{ lang('order_by') }}
                 </button>
-                <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
+                <div class="dropdown-menu shadow-sm" aria-labelledby="dropdownMenuButton">
                     <a class="dropdown-item" href="{{ queryParams({'sort':'time'}) }}"><i class="fas fa-calendar-alt fa-fw"></i> {{ lang('time') }}</a>
                     <a class="dropdown-item" href="{{ queryParams({'sort':'name'}) }}"><i class="fas fa-font fa-fw"></i> {{ lang('name') }}</a>
                     <a class="dropdown-item" href="{{ queryParams({'sort':'size'}) }}"><i class="fas fa-weight-hanging fa-fw"></i> {{ lang('size') }}</a>